Sample Surveys. The two most typical sources of bias are selection bias and nonresponse bias.


 Arline Greer
 10 months ago
 Views:
Transcription
1 Sample Surveys In this class we will consider the problem of sampling from a finite population. This is usually referred to as a survey. The goal of the survey is to learn about some parameters of a population, like averages or proportions. A well designed survey avoids systematic biases. The two most typical sources of bias are selection bias and nonresponse bias.
2 Collecting data: Sample Surveys A population is a class of individuals that an investigator is interested in. Examples of populations are 1. All eligible voters in a presidential election. 2. All facebook users that live in Santa Cruz. 3. The female elephant seals that mate at Año Nuevo State Reserve during the winter. 4. All ford focus drivers. A full examination of a population requires a census. This may be impractical in many cases. If only one part of the population is examined, then we are looking at a sample. The goal is to make inferences from the sample to the whole population.
3 Collecting data: Sample Surveys There are usually some numerical characteristics of the population that we are interested in. These are called parameters. For example 1. The average age of eligible voters. 2. The average income of facebook users in Santa Cruz. 3. The proportion of puppies per female elephant seal. 4. The average number of miles driven in a week. Parameters are unknown quantities which are estimated using statistics, which are numbers that can be computed from the sample. The validity of those values depends of how well the sample represents the population.
4 A biased poll Before the 1936 presidential election the The literary Digest, a very prestigious magazine, predicted that Roosevelt will loose the election to Landon obtaining only 43% of the votes. The result of the election was that Roosevelt won by a landslide 62% to 38%. Why was the Literary Digest so wrong? Because their poll was badly designed The Digest based its prediction on a sample of 2.4 million people who responded to a mailed questionnaire that was sent to 10 million people. The names and addresses of these people were obtained from telephone books and club membership lists.
5 The sample had a strong bias against the poor, since they were unlikely to belong to clubs or have phones (in the 30s). The outcome of the election showed a split that followed a clear economic line: the poor voted for Roosevelt and the rich were with Landon. Taking a large number of samples when the procedure has a bias does not improve the results Another source of bias in the Digest s poll is that there was a large number of nonrespondents. This produces a nonresponse bias, since nonrespondents can be very different to respondents.
6 Studies have shown that people from the middle class are more likely to respond that people from the upper or the lower classes. So in a survey with a high nonresponse rate, middle class people may be overrepresented. When considering the quality of a survey keep in mind two possible sources of bias: Selection bias Nonresponse bias
7 Quota Sampling Consider the following scheme to obtain a sample. You send an interviewer to the field and ask him or her to get a fixed number of interviews within certain categories. For example: Interview 13 subjects Exactly 6 from the suburbs, 7 from the central city. Exactly 7 men and 6 women Of the men, 3 have to be under forty, 4 above forty. Of the men, 1 has to be black and 6 white. The list of restrictions could go on. The goal is to achieve a sample that is fairly indicative of all demographic and social characteristics of the population to make it representative. This is called a quota sampling scheme.
8 But, at the end, the interviewer has the freedom of deciding who gets interviewed, that is, the ultimate selection is left to human wisdom. Gallup polls were conducted using the quota system for more than a decade, these are the results regarding the Republican vote: Year Prediction Results Errors % 38% 6% % 45% 3% % 46% 2% % 45% 4% The sample sizes are around 50,000. In the 1948 election, Gallup predicted the wrong winner. Gallup had a systematic bias in favor of the Republican candidate in all elections from 36 to 48.
9 The reason for the bias is twofold: 1. The sample mimics the population in all possible variables that are controlled for, but there are still other factors that influence the voting behavior of subjects in the sample. 2. There could be an unintentional bias of the interviewers. For example, Republicans might have been easier to interview and so more likely to be picked by an interviewer.
10 Using chance To eliminate the selection bias in a sample we use chance in choosing the individuals to be included in the sample. How does it work? We first set the size of the sample we need. From a list of the subjects in the population (the sample frame) we take one by chance. We delete that subject from the list and take a second subject by chance from the remaining ones. The process continues until we have completed the sample. This is called simple random sampling. The subjects have been drawn at random without replacement.
11 A real poll Using a sample based on chance eliminates selection bias, but a simple random sample can be difficult and costly when the population is large. Also, a simple random sample disregards valuable information about the characteristics of the population. A better idea is to consider a sampling scheme that consists of multiple stages, each one is subject to chance. The Gallup poll after the 1948 election is an example. The poll is taken as follows: 1. The Nation is split in 4 regions: W, MW, NE and S. All population centers of similar size are grouped together. 2. A random sample of the towns is selected. No interviews are conducted in the towns not in the sample. 3. Each town is divided in wards and the wards are subdivided into precincts. 4. Some wards are selected at random within the selected towns. 5. Some precincts are selected at random within the selected wards. 6. Some households are selected at random within the selected precincts. 7. Some members of the selected households are interviewed. This is called a multistage cluster sampling scheme.
12 The results The following table presents the results of Gallup s predictions for some elections from 1952 to Year sample size Won Prediction Result Error ,385 Eisenhower 51% 55.4% 4.4% ,015 Kennedy 51% 50.1%.9% ,414 Nixon 43% 43.5%.5% ,439 Carter 49.5% 51.1% 1.6% ,089 Reagan 59% 59.2%.2% ,019 Clinton 49.0% 43.2% 5.8% We observe a much smaller error (except for the 1992 election), no bias in favor of the Republican candidate and much smaller sample sizes.
13 Problems Investigators doing polls have to face several problems that can bias the results of the survey even after considering a probabilistic sample. Nonvoters: Usually between 30% and 50% of the eligible voters don t vote. But many of these are tempted to respond affirmatively when asked about their voting intentions. Interviewers ask indirect questions that allow to check if the person is genuinely a voter or not. Undecided: Polls ask questions that give information about the political attitudes of the interviewed person in order to forecast the vote of undecided voters. Response bias: Questions can be posed in a way that bias the response. A useful tool is to have the interviewed person deposit a ballot in a box. Nonresponse bias: As discussed before, this can create a bias since nonrespondents are different from the rest. This is usually corrected by giving more weight to people who are difficult to get, since they, somehow, represent a subpopulation which is closer to the nonrespondents.
14 Telephone surveys Conducting a survey by phone saves money. It can also be done in less time. How do you select sample? Phone numbers look like this Area code Exchange Bank Digits The Gallup poll in 88 used a multistage cluster sample using area codes, exchanges, banks and digits as a hierarchy. The Gallup poll in 92 was simpler and worked like this: 1. There are 4 time zones in the US. Each zone is divided in 3 types of areas: heavy, medium and lightly populated areas. This produced 12 sampling regions. 2. They sampled numbers at random within each region.
15 Problems Problem 1: A survey organization is planning an opinion survey of 2,500 people of voting age in the U.S.. True or false and explain: the organization will choose people to interview by taking a simple random sample. This is false. Taking a simple random sample of a population of about 200 million voters is impractical. First because a list of all the voters is not available. Second because taking a simple random sample of such a list is a big problem in itself and third because interviewing 2,500 people all scattered around the map will be very costly. Problem 2: A sample of JapaneseAmerican residents in San Francisco is taken by considering the four most representative blocks in the Japanese area of the town and interviewing all the residents in those areas. However, a comparison with Census data shows that the sample did not include a high enough proportion of Japanese with college degrees. How can this be explained? This was not a good way to draw the sample because you would expect that people living in the more traditional areas have very specific characteristics. In particular, it is likely that people with college degrees were living in more suburban neighborhoods.
16 Histograms Information is available from 131 hospitals. We show a histogram of the average length of stay measured in days for each hospital. The area of each block is proportional to the number of hospitals in the corresponding class interval. Histogram of the average length of stay in hospital length of stay (days) In this example all the intervals have the same length.
17 There are 7 class intervals corresponding to 6 to 8 days 8 to 10 days 10 to 12 days 12 to 14 days 14 to 16 days 16 to 18 days 18 to 20 days Note that the class that corresponds to 14 to 16 days is empty and that the class with the highest count of hospitals is the one of 8 to 10 days.
18 Income level in $ percent 0 1, ,000 2, ,000 3, ,000 4, ,000 5, ,000 6, ,000 7, ,000 10, ,000 15, ,000 25, ,000 50, ,000 and over 1 Drawing a histogram The starting point of a histogram is a distribution table. Consider the distribution of families by income in the US in In this table class intervals include the left point, but not the right point. It is important to specify which of the endpoints are included in each class. Notice that in this case class intervals do not have the same length.
19 Once the distribution table is available the next step is to draw a horizontal axis specifying the class intervals. Then we draw the blocks remembering that In a histogram, the areas of the blocks represent percentages So, it is a mistake to set the heights of the blocks equal to the percentages in the table. The area of a rectangle is height width, A = h w If we know the percent is equal to the area, and we know the width of the class interval, we find the height by dividing the above equation by width A w = h This means that the height has units of percent per class interval. The table needed to calculate the heights of the blocks looks like
20 Income level in $ percent width in $ percent per $ , ,000 2, ,000 3, ,000 4, ,000 5, ,000 6, ,000 7, ,000 10, ,000 15, ,000 25, ,000 50, ,000 and over 1
21 Distribution of family income in the US in 1973 percent per $ This is the resulting histogram. Notice that the class interval of incomes above $50,000 has been ignored income in $1000
22 Vertical scale What is the meaning of the vertical scale in a histogram? Remember that the area of the blocks is proportional to the percents. A high height implies that large chunks of area accumulate in small portions of the horizontal scale. This implies that the density or concentration of the data is high in the intervals where the height is large. In other words, the data are more crowded in those intervals.
23 Types of variables A variable is a characteristic that may change from individual to individual in a population. For example, in a survey the questions: how old are you? What is your family s size? What is your gender? What is your marital status? Correspond to the variables: age, size, sex and marital status. There are different types of variables. Each type is usually handled and analyzed differently.
24 Variables can be classified as: Quantitative data. Correspond to observations measured on a numerical scale. This can be: Discrete when the values can differ by fixed amounts like in size. This is typical of counts. Continuous differences in values can be arbitrarily small like in age. This is typical of variables that measure physical quantities. Qualitative data. Correspond to observations classified in groups or categories like in sex and marital status. Sometimes the groups have some ordering, as in the case of grades. Of particular importance are binary variables that can take only two values.
25 Classify the following variables: Records of whether an electrical device is working or not. The depth of the snow pack at a monitoring station in the Sierras. The number of students in AMS 5. The final grade of a student in AMS 5. The State where a given car is registered. The ranking of a school within the State school system. The number of calls to 911 in a given month
Introduction to Statistics
1 1.1 Introduction Introduction to Statistics Statistics is a collection of methods for planning experiments, obtaining data, and then organizing, summarizing, presenting, analyzing, interpreting and drawing
More informationElementary Statistics
Elementary Statistics Chapter 1 Dr. Ghamsary Page 1 Elementary Statistics M. Ghamsary, Ph.D. Chap 01 1 Elementary Statistics Chapter 1 Dr. Ghamsary Page 2 Statistics: Statistics is the science of collecting,
More informationStatistics Notes Revision in Maths Week
Statistics Notes Revision in Maths Week 1 Section  Producing Data 1.1 Introduction Statistics is the science that studies the collection and interpretation of numerical data. Statistics divides the study
More information1.1 What is statistics? Data Collection. Important Definitions. What is data? Descriptive Statistics. Inferential Statistics
1.1 What is statistics? Data Collection Chapter 1 A science (bet you thought it was a math) of Collecting of data (Chap. 1) Organizing data (Chap. 2) Summarizing data (Chap. 2, 3) Analyzing data (Chap.
More informationSHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
Ch. 1 Introduction to Statistics 1.1 An Overview of Statistics 1 Distinguish Between a Population and a Sample Identify the population and the sample. survey of 1353 American households found that 18%
More informationSAMPLING METHODS. Chapter 5
SAMPLING METHODS Chapter 5 1 LEARNING OBJECTIVES Reasons for sampling Different sampling methods Probability & non probability sampling Advantages & disadvantages of each sampling method 2 SAMPLING A sample
More informationAn Introduction to Sampling
An Introduction to Sampling Sampling is the process of selecting a subset of units from the population. We use sampling formulas to determine how many to select because it is based on the characteristics
More informationSAMPLING DISTRIBUTIONS
0009T_c07_308352.qd 06/03/03 20:44 Page 308 7Chapter SAMPLING DISTRIBUTIONS 7.1 Population and Sampling Distributions 7.2 Sampling and Nonsampling Errors 7.3 Mean and Standard Deviation of 7.4 Shape of
More informationUNF Poll reveals Hillary Clinton holding on to her lead in the Democratic Primary race.
February 29, 2016 Media Contact: Joanna Norris, Associate Director Department of Public Relations (904) 6202192 UNF Poll reveals Hillary Clinton holding on to her lead in the Democratic Primary race.
More informationMind on Statistics. Chapter 10
Mind on Statistics Chapter 10 Section 10.1 Questions 1 to 4: Some statistical procedures move from population to sample; some move from sample to population. For each of the following procedures, determine
More informationSurvey Sampling. Know How No 9 guidance for research and evaluation in Fife. What this is about? Who is it for? What do you need to know?
guidance for research and evaluation in Fife What this is about? Sampling allows you to draw conclusions about a particular population by examining a part of it. When carrying out a survey, it is not usually
More informationSampling Procedures Y520. Strategies for Educational Inquiry. Robert S Michael
Sampling Procedures Y520 Strategies for Educational Inquiry Robert S Michael RSMichael 21 Terms Population (or universe) The group to which inferences are made based on a sample drawn from the population.
More informationReflections on Probability vs Nonprobability Sampling
Official Statistics in Honour of Daniel Thorburn, pp. 29 35 Reflections on Probability vs Nonprobability Sampling Jan Wretman 1 A few fundamental things are briefly discussed. First: What is called probability
More informationSamples and Surveys. Objectives To identify sampling methods To recognize bias in samples and surveys
CC19 Samples and Surveys Objectives To identify sampling methods To recognize bias in samples and surveys Common Core State Standards MACC.912.SIC.1.1 Understand statistics as a process for making inferences
More informationTHE FIELD POLL. By Mark DiCamillo, Director, The Field Poll
THE FIELD POLL THE INDEPENDENT AND NONPARTISAN SURVEY OF PUBLIC OPINION ESTABLISHED IN 1947 AS THE CALIFORNIA POLL BY MERVIN FIELD Field Research Corporation 601 California Street, Suite 210 San Francisco,
More informationUnit 1: Research Design, Sampling & Measurement
Unit 1: Research Design, Sampling & Measurement irat You have 10 minutes to do it Mark your answer on both answer sheet and question sheet Turn in the answer sheet GOG502/PLN504 Youqin Huang 1 GOG502/PLN504
More informationALABAMA and OKLAHOMA: TRUMP LEADS IN BOTH CLINTON LEADS IN AL, SANDERS IN OK
Please attribute this information to: Monmouth University Poll West Long Branch, NJ 07764 www.monmouth.edu/polling Follow on Twitter: @MonmouthPoll Released: Monday, February 29, 2016 Contact: PATRICK
More informationPie Charts. proportion of icecream flavors sold annually by a given brand. AMS5: Statistics. Cherry. Cherry. Blueberry. Blueberry. Apple.
Graphical Representations of Data, Mean, Median and Standard Deviation In this class we will consider graphical representations of the distribution of a set of data. The goal is to identify the range of
More informationTHE FIELD POLL. By Mark DiCamillo, Director, The Field Poll
THE FIELD POLL THE INDEPENDENT AND NONPARTISAN SURVEY OF PUBLIC OPINION ESTABLISHED IN 1947 AS THE CALIFORNIA POLL BY MERVIN FIELD Field Research Corporation 601 California Street, Suite 210 San Francisco,
More informationAGAINST ALL ODDS EPISODE 17 SAMPLES AND SURVEYS TRANSCRIPT
AGAINST ALL ODDS EPISODE 17 SAMPLES AND SURVEYS TRANSCRIPT 1 FUNDER CREDITS Funding for this program is provided by Annenberg Learner. 2 INTRO Hi, I m and this is Against All Odds, where we make statistics
More informationCarolyn Anderson & Youngshil Paek (Slides created by Shuai Sam Wang) Department of Educational Psychology University of Illinois at UrbanaChampaign
Carolyn Anderson & Youngshil Paek (Slides created by Shuai Sam Wang) Department of Educational Psychology University of Illinois at UrbanaChampaign Key Points 1. Data 2. Variable 3. Types of data 4. Define
More informationTHE FIELD POLL. By Mark DiCamillo, Director, The Field Poll
THE FIELD POLL THE INDEPENDENT AND NONPARTISAN SURVEY OF PUBLIC OPINION ESTABLISHED IN 1947 AS THE CALIFORNIA POLL BY MERVIN FIELD Field Research Corporation 601 California Street, Suite 210 San Francisco,
More informationHow to Vote! A WORKBOOK BY STUDENTS FOR STUDENTS. California Edition
How to Vote! A WORKBOOK BY STUDENTS FOR STUDENTS California Edition CONTENTS This workbook was put together by adult reading students (also called learners ) to help other students learn more about voting.
More informationAP Statistics Chapters 1112 Practice Problems MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
AP Statistics Chapters 1112 Practice Problems Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Criticize the following simulation: A student
More information14.30 Introduction to Statistical Methods in Economics Spring 2009
MIT OpenCourseWare http://ocw.mit.edu 14.30 Introduction to tatistical Methods in Economics pring 2009 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms.
More informationTEXAS: CRUZ, CLINTON LEAD PRIMARIES
Please attribute this information to: Monmouth University Poll West Long Branch, NJ 07764 www.monmouth.edu/polling Follow on Twitter: @MonmouthPoll Released: Thursday, 25, Contact: PATRICK MURRAY 7329796769
More informationMARYLAND: CLINTON LEADS SANDERS BY 25
Please attribute this information to: Monmouth University Poll West Long Branch, NJ 07764 www.monmouth.edu/polling Follow on Twitter: @MonmouthPoll Released: Thursday, 21, Contact: PATRICK MURRAY 7329796769
More informationRelease #2343 Release Date: Saturday, July 10, 2010
THE FIELD POLL THE INDEPENDENT AND NONPARTISAN SURVEY OF PUBLIC OPINION ESTABLISHED IN 1947 AS THE CALIFORNIA POLL BY MERVIN FIELD Field Research Corporation 601 California Street, Suite 900 San Francisco,
More informationIntroduction... 3. Qualitative Data Collection Methods... 7 In depth interviews... 7 Observation methods... 8 Document review... 8 Focus groups...
1 Table of Contents Introduction... 3 Quantitative Data Collection Methods... 4 Interviews... 4 Telephone interviews... 5 Face to face interviews... 5 Computer Assisted Personal Interviewing (CAPI)...
More informationWhy Sample? Why not study everyone? Debate about Census vs. sampling
Sampling Why Sample? Why not study everyone? Debate about Census vs. sampling Problems in Sampling? What problems do you know about? What issues are you aware of? What questions do you have? Key Sampling
More informationNeed for Sampling. Very large populations Destructive testing Continuous production process
Chapter 4 Sampling and Estimation Need for Sampling Very large populations Destructive testing Continuous production process The objective of sampling is to draw a valid inference about a population. 4
More informationDescriptive Inferential. The First Measured Century. Statistics. Statistics. We will focus on two types of statistical applications
Introduction: Statistics, Data and Statistical Thinking The First Measured Century FREC 408 Dr. Tom Ilvento 213 Townsend Hall ilvento@udel.edu http://www.udel.edu/frec/ilvento http://www.pbs.org/fmc/index.htm
More informationTechniques for data collection
Techniques for data collection Technical workshop on survey methodology: Enabling environment for sustainable enterprises in Indonesia Hotel Ibis Tamarin, Jakarta 46 May 2011 Presentation by Mohammed
More informationOnline International Interdisciplinary Research Journal, {BiMonthly}, ISSN22499598, VolumeII, IssueVI, NovDec 2012
Methods of Sampling Design in the Legal Research: Advantages and Disadvantages Kalpana V. Jawale Assistant Professor, Post Graduate Teaching Department of Law, Sant Gadge Baba Amravati University, Amravati,
More informationMadelyn Hochstein, President, DYG, Inc. for her care, counsel and determined efforts in editing these TIPS;
ACKNOWLEDGMENTS With unbounded appreciation, I thank: Madelyn Hochstein, President, DYG, Inc. for her care, counsel and determined efforts in editing these TIPS; The Alfred P. Sloan Foundation for its
More informationChapter 20: chance error in sampling
Chapter 20: chance error in sampling Context 2 Overview................................................................ 3 Population and parameter..................................................... 4
More informationLiterature Review of Sample Design and Methods
Literature Review of Sample Design and Methods Generally, a researcher employs sampling strategies in order to generate statistics and generalize findings to a larger population. Sampling refers to the
More informationFlorida Poll Results Trump 47%, Clinton 42% (Others 3%, 8% undecided) Rubio reelect: 3839% (22% undecided)
Florida Poll Results Trump 47%, Clinton 42% (Others 3%, 8% undecided) Rubio reelect: 3839% (22% undecided) POLLING METHODOLOGY Our philosophy about which population to use depends on the election, but
More informationVIRGINIA: TRUMP, CLINTON LEAD PRIMARIES
Please attribute this information to: Monmouth University Poll West Long Branch, NJ 07764 www.monmouth.edu/polling Follow on Twitter: @MonmouthPoll Released: Thursday, 25, Contact: PATRICK MURRAY 7329796769
More informationSAMPLING METHODS IN SOCIAL RESEARCH
SAMPLING METHODS IN SOCIAL RESEARCH Muzammil Haque Ph.D Scholar Visva Bharati, Santiniketan,West Bangal Sampling may be defined as the selection of some part of an aggregate or totality on the basis of
More informationWelcome back to EDFR 6700. I m Jeff Oescher, and I ll be discussing quantitative research design with you for the next several lessons.
Welcome back to EDFR 6700. I m Jeff Oescher, and I ll be discussing quantitative research design with you for the next several lessons. I ll follow the text somewhat loosely, discussing some chapters out
More information4. Introduction to Statistics
Statistics for Engineers 41 4. Introduction to Statistics Descriptive Statistics Types of data A variate or random variable is a quantity or attribute whose value may vary from one unit of investigation
More informationLesson 2: Calculating Probabilities of Events Using TwoWay Tables
Calculating Probabilities of Events Using TwoWay Tables Classwork Example 1: Building a New High School The school board of Waldo, a rural town in the Midwest, is considering building a new high school
More informationSampling. by David A. Freedman Department of Statistics University of California Berkeley, CA 94720
Sampling by David A. Freedman Department of Statistics University of California Berkeley, CA 94720 The basic idea in sampling is extrapolation from the part to the whole from the sample to the population.
More informationThe American Panel Survey
Draft: To be updated in June Guide for Investigators The American Panel Survey Weidenbaum Center Washington University James L. Gibson and Steven S. Smith, Directors About The American Panel Survey (TAPS)
More informationAUGUST 2014 TOPLINE RESULTS
AUGUST 2014 TOPLINE RESULTS RELEASED: AUGUST 2014 The ReasonRupe August 2014 Poll interviewed 1,000 adults on both mobile (500) and landline (500) phones, including 291 respondents without landlines,
More informationStatistics 2014 Scoring Guidelines
AP Statistics 2014 Scoring Guidelines College Board, Advanced Placement Program, AP, AP Central, and the acorn logo are registered trademarks of the College Board. AP Central is the official online home
More informationChapter 1: The Nature of Probability and Statistics
Chapter 1: The Nature of Probability and Statistics Learning Objectives Upon successful completion of Chapter 1, you will have applicable knowledge of the following concepts: Statistics: An Overview and
More informationMidterm Review Problems
Midterm Review Problems October 19, 2013 1. Consider the following research title: Cooperation among nursery school children under two types of instruction. In this study, what is the independent variable?
More informationAP STATISTICS TEST #2  REVIEW  Ch. 14 &15 Period:
AP STATISTICS Name TEST #2  REVIEW  Ch. 14 &15 Period: 1) The city council has 6 men and 3 women. If we randomly choose two of them to cochair a committee, what is the probability these chairpersons
More informationUNO Survey Research Center
2015 LOUISIANA GUBERNATORIAL RUNOFF SURVEY November 2015 UNO Survey Research Center Dr. Edward E. Chervenak, Director echerven@uno.edu Elizabeth Juhasz, Research Assistant emjuhasz@uno.edu Deborah Toscano,
More informationBasic Principles of Survey Design. Thomas Lindsay Andrew Sell
Basic Principles of Survey Design Thomas Lindsay Andrew Sell Introductions Name, Institution, why are you here? Survey Review 5 minutes Political Participation and Attitudes Survey What is the research
More informationData Collection and Sampling OPRE 6301
Data Collection and Sampling OPRE 6301 Recall... Statistics is a tool for converting data into information: Statistics Data Information But where then does data come from? How is it gathered? How do we
More informationHow are polls conducted? by Frank Newport, Lydia Saad, David Moore from Where America Stands, 1997 John Wiley & Sons, Inc.
How are polls conducted? by Frank Newport, Lydia Saad, David Moore from Where America Stands, 1997 John Wiley & Sons, Inc. Public opinion polls would have less value in a democracy if the public  the
More informationStatewide Survey of Louisiana Likely Voters on David Duke
Statewide Survey of Louisiana Likely Voters on David Duke The University of New Orleans Survey Research Center (SRC) sponsored an automated interactive voice response (IVR) telephone survey of likely Louisiana
More informationMargin of Error When Estimating a Population Proportion
Margin of Error When Estimating a Population Proportion Student Outcomes Students use data from a random sample to estimate a population proportion. Students calculate and interpret margin of error in
More informationName: Date: Use the following to answer questions 23:
Name: Date: 1. A study is conducted on students taking a statistics class. Several variables are recorded in the survey. Identify each variable as categorical or quantitative. A) Type of car the student
More informationSurvey Research. Classifying surveys on the basis of their scope and their focus gives four categories:
Survey Research Types of Surveys Surveys are classified according to their focus and scope (census and sample surveys) or according to the time frame for data collection (longitudinal and crosssectional
More informationMICHIGAN: TRUMP, CLINTON IN FRONT
Please attribute this information to: Monmouth University Poll West Long Branch, NJ 07764 www.monmouth.edu/polling Follow on Twitter: @MonmouthPoll Released: Monday, 7, Contact: PATRICK MURRAY 7329796769
More informationOHIO: KASICH, TRUMP IN GOP SQUEAKER; CLINTON LEADS IN DEM RACE
Please attribute this information to: Monmouth University Poll West Long Branch, NJ 07764 www.monmouth.edu/polling Follow on Twitter: @MonmouthPoll Released: Monday, 14, Contact: PATRICK MURRAY 7329796769
More informationRelease #2301 Release Date and Time: 6:00 a.m., Tuesday, March 10, 2009
THE FIELD POLL THE INDEPENDENT AND NONPARTISAN SURVEY OF PUBLIC OPINION ESTABLISHED IN 1947 AS THE CALIFORNIA POLL BY MERVIN FIELD Field Research Corporation 601 California Street, Suite 900 San Francisco,
More informationPolitical Parties and the Party System
California Opinion Index A digest on how the California public views Political Parties and the Party System April 1999 Findings in Brief The proportion of Californians who follows what s going on in government
More informationThe Town of the Blue Mountains
The Town of the Blue Mountains 2015 Citizen Satisfaction Survey KEY FINDINGS REPORT 1 Table of Contents Background and Methodology... 3 Background and Objectives:... 3 Questions and Analysis... 3 Derived
More informationSTATISTICS 8 CHAPTERS 1 TO 6, SAMPLE MULTIPLE CHOICE QUESTIONS
STATISTICS 8 CHAPTERS 1 TO 6, SAMPLE MULTIPLE CHOICE QUESTIONS Correct answers are in bold italics.. This scenario applies to Questions 1 and 2: A study was done to compare the lung capacity of coal miners
More informationTYPES OF SAMPLING. 2. Types of Nonprobability Sample: There are the following four types of nonprobability PROBABILITY SAMPLING
TYPES OF SAMPLING 1. Types or Techniques Probability Sampling: There are a number of techniques of taking Probability sample. But here only six important techniques have been discussed as follows: 1. Simple
More informationNUMBERS, FACTS AND TRENDS SHAPING THE WORLD FOR RELEASE NOVEMBER 3, 2014 FOR FURTHER INFORMATION ON THIS REPORT: Aaron Smith, Senior Researcher
NUMBERS, FACTS AND TRENDS SHAPING THE WORLD FOR RELEASE NOVEMBER 3, 2014 FOR FURTHER INFORMATION ON THIS REPORT: Aaron Smith, Senior Researcher 202.419.4372 RECOMMENDED CITATION: Pew Research Center, November,
More informationbehavior research center s
behavior research center s behavior research center s NEWS RELEASE [RMP 2012III01] Contact: Earl de Berge Research Director 6022584554 6022686563 OBAMA PULLS EVEN WITH ROMNEY IN ARIZONA; FLAKE AND
More informationComparative Study of Electoral Systems (CSES) Module 4: Design Report (Sample Design and Data Collection Report) February 2, 2014
Comparative Study of Electoral Systems 1 Comparative Study of Electoral Systems (CSES) (Sample Design and Data Collection Report) February 2, 2014 Country: Mexico Date of Election: June 7 th, 2015 Prepared
More informationTHE FIELD POLL. By Mark DiCamillo, Director, The Field Poll
THE FIELD POLL THE INDEPENDENT AND NONPARTISAN SURVEY OF PUBLIC OPINION ESTABLISHED IN 1947 AS THE CALIFORNIA POLL BY MERVIN FIELD Field Research Corporation 601 California Street, Suite 210 San Francisco,
More informationWestern New England University Polling Institute
WESTERN NEW ENGLAND UNIVERSITY Western New England University Polling Institute Massachusetts Statewide Telephone Survey September 2028, 2014 Dr. Tim Vercellotti For Immediate Release TABLES Next, please
More informationSampling and Sampling Distributions
Sampling and Sampling Distributions Random Sampling A sample is a group of objects or readings taken from a population for counting or measurement. We shall distinguish between two kinds of populations
More informationDetermine whether the data are qualitative or quantitative. 8) the colors of automobiles on a used car lot Answer: qualitative
Name Score: Math 227 Review Exam 1 Chapter 2& Fall 2011 ********************************************************************************************************************** SHORT ANSWER. Show work on
More informationIntroduction to Statistics for the Life Sciences
Introduction to Statistics for the Life Sciences Fall 2014 Volunteer Definition A biased sample systematically overestimates or underestimates a characteristic of the population Paid subjects for drug
More informationVoter Participation: Who s Voting?
University of Virginia Center for Politics Voter Participation: Who s Voting? Purpose: Voting in state, local, and federal elections is an integral component of citizenship and yet only sixtyfour percent
More informationPresenting numerical data
Student Learning Development Presenting numerical data This guide offers practical advice on how to incorporate numerical information into essays, reports, dissertations, posters and presentations. The
More informationSampling Designs. 1. Simple random sampling (SRS) Steps: The method is not very different from winning a lottery.
Sampling Designs 1. Simple random sampling (SRS) Steps: (1) Assign a single number to each element in the sampling frame. (2) Use random numbers to select elements into the sample until the desired number
More informationNorthumberland Knowledge
Northumberland Knowledge Know Guide How to Analyse Data  November 2012  This page has been left blank 2 About this guide The Know Guides are a suite of documents that provide useful information about
More informationComparative Study of Electoral Systems (CSES) Module 3: Sample Design and Data Collection Report
Comparative Study of Electoral Systems 1 Comparative Study of Electoral Systems (CSES) Module 3: Sample Design and Data Collection Report Country: México. Date of Election: July, 5 2009. Prepared by: CIDE.
More informationSelecting Research Participants
C H A P T E R 6 Selecting Research Participants OBJECTIVES After studying this chapter, students should be able to Define the term sampling frame Describe the difference between random sampling and random
More informationThe Five Rules for Reliable Marketing Research
URBAN WALLACE ASSOCIATES 35 Bedford St., Suite 8, Lexington, MA 02420 ph 781 862 0033 fax 781 862 1292 web www.uwa.com The Five Rules for Reliable Marketing Research Marketing Research Produces New Knowledge
More informationElections polling Sample and methodology
Elections polling Sample and methodology Traditionally telephone surveys have been conducted by landline. In Afghanistan however, as is the case in many developing countries where the large scale uptake
More informationSampling. COUN 695 Experimental Design
Sampling COUN 695 Experimental Design Principles of Sampling Procedures are different for quantitative and qualitative research Sampling in quantitative research focuses on representativeness Sampling
More informationGraphical and Tabular. Summarization of Data OPRE 6301
Graphical and Tabular Summarization of Data OPRE 6301 Introduction and Recap... Descriptive statistics involves arranging, summarizing, and presenting a set of data in such a way that useful information
More informationFREQUENCY AND PERCENTILES
FREQUENCY DISTRIBUTIONS AND PERCENTILES New Statistical Notation Frequency (f): the number of times a score occurs N: sample size Simple Frequency Distributions Raw Scores The scores that we have directly
More informationNATIONAL: TRUMP WIDENS LEAD
Please attribute this information to: Monmouth University Poll West Long Branch, NJ 07764 www.monmouth.edu/polling Follow on Twitter: @MonmouthPoll Released: Monday, August 3, Contact: PATRICK MURRAY 7329796769
More informationNonrandom/nonprobability sampling designs in quantitative research
206 RESEARCH MET HODOLOGY Nonrandom/nonprobability sampling designs in quantitative research N onprobability sampling designs do not follow the theory of probability in the choice of elements from the
More informationTelephone and Mail Surveys: Advantages and Disadvantages of Each
Telephone and Mail Surveys: Advantages and Disadvantages of Each Dan Zahs and Reg Baker Market Strategies, Inc. May 29, 2007 Selecting the mode of administration for a survey requires that one evaluate
More informationThe Math. P (x) = 5! = 1 2 3 4 5 = 120.
The Math Suppose there are n experiments, and the probability that someone gets the right answer on any given experiment is p. So in the first example above, n = 5 and p = 0.2. Let X be the number of correct
More informationGroup Unweighted N Plus or minus Total sample 5,113 2.0 percentage points
METHODOLOGY The NBC News Online Survey was conducted online by SurveyMonkey September 168, 2015 among a national sample of 5,113 adults aged 18 and over. Respondents for this nonprobability survey were
More informationa) Construct a comparative Dotplot for protein content for the two groups of plants.
AP Statistics Fall exam review Problems 1. A treatment that has no active ingredients is called a(n). 2. A sample consisting of the entire population is called a(n). 3. is the tendency for a sample to
More informationVoting and Political Demography in 1996
California Opinion Index A review of Voting and Political Demography in 1996 February 1997 Findings in Brief Approximately 10.3 million Californians voted in the November 1996 Presidential elections, down
More informationRacial and Ethnic Diversity in Anaheim
Racial and Ethnic Diversity in Anaheim Anaheim s racial and ethnic demographics have changed dramatically in the last thirty years. Asian/Pacific Islander 4.1% Other 1.2% Hispanic/ Latino 1.1% Black/African
More informationTHE FIELD POLL. By Mark DiCamillo, Director, The Field Poll
THE FIELD POLL THE INDEPENDENT AND NONPARTISAN SURVEY OF PUBLIC OPINION ESTABLISHED IN 1947 AS THE CALIFORNIA POLL BY MERVIN FIELD Field Research Corporation 601 California Street, Suite 210 San Francisco,
More informationFrom awareness to funding
From awareness to funding Chapter 1 From awareness to funding This report summarizes the research findings of an advocacy research grant awarded to OCLC by the Bill & Melinda Gates Foundation. The grant
More information17% of cell phone owners do most of their online browsing on their phone, rather than a computer or other device
JUNE 26, 2012 17% of cell phone owners do most of their online browsing on their phone, rather than a computer or other device Most do so for convenience, but for some their phone is their only option
More informationMath 251, Review Questions for Test 3 Rough Answers
Math 251, Review Questions for Test 3 Rough Answers 1. (Review of some terminology from Section 7.1) In a state with 459,341 voters, a poll of 2300 voters finds that 45 percent support the Republican candidate,
More informationFLORIDA: TRUMP WIDENS LEAD OVER RUBIO
Please attribute this information to: Monmouth University Poll West Long Branch, NJ 07764 www.monmouth.edu/polling Follow on Twitter: @MonmouthPoll Released: Monday, March 14, Contact: PATRICK MURRAY 7329796769
More informationSurvey Research. Writing Questionnaire Items. Likerttype Scales. Label the endpoints only Label endpoints and middle Label every point on the scale
Survey Research Claudia J. Stanny PSY 6217 Research Design Writing Questionnaire Items Openended items Partially openended items Closed (Restricted) items Provide a choice for all potential responses
More informationNEW HAMPSHIRE: TRUMP, SANDERS HOLD LEADS
Please attribute this information to: Monmouth University Poll West Long Branch, NJ 07764 www.monmouth.edu/polling Follow on Twitter: @MonmouthPoll Released: Sunday, 7, Contact: PATRICK MURRAY 7329796769
More information2016 California GOP Presidential Primary Poll
2016 California GOP Presidential Primary Poll To test potential and probable presidential candidates for the June 7 th, 2016 California Republican Presidential Primary election, NSON Opinion Strategy,
More information