SPSS Tutorial, Feb. 7, 2003 Prof. Scott Allard

Transcription

1 p. 1 SPSS Tutorial, Feb. 7, 2003 Prof. Scott Allard The following tutorial is a guide to some basic procedures in SPSS that will be useful as you complete your data assignments for PPA 722. The purpose of this tutorial is to show you how to use SPSS, not to help you interpret the statistical output you create. In addition to this tutorial, reference the following websites for assistance with SPSS: The tutorial will use a file titled spss_tutorial.sav that you can find on the M-drive (classes drive) in the folder Allard PPA 722. In addition to spss_tutorial.sav, is a syntax file titled spss_tutorial.sps. The data file consists of 330 records with data on welfare recipients participating in a welfare-to-work program. Variables included in the file: RACE Race of the Respondent AGE Age of the Respondent KIDS Number of Children in the Household LESSHS Educational Attainment of the Respondent AUTO Whether Respondent Has Access to a Car JOBACC Measure of Job Access (Higher score = greater job access) PTMWORK Percentage of Months Worked in 1998 ANN_EARN Annual Earnings in ) Open SPSS. Basic Data Management in SPSS 2) Go to File, Open, Data. Open data file, M:\ Allard PPA 722\ spss_tutorial.sav 3) We are going to create a recoded variable for age, which is currently continuous. - Go to Transform, Recode, Into Different Variables - Select age and move it over to the input/output variable box with the arrow key - Click the name box and type in age_rc - Click on the label box and type Age Recode - Click Change button - Click Old and New Values button

2 p. 2 - Under Old Value, click on Range, and enter age range 18 to 24 - Under New Value, type in 1 and click Add button - Repeat these last two steps using the following ranges and values: 25 to 34 = 2 35 to 44 = 3 45 to 64 = 4 - Click Continue 4) Creating Value Labels for a variable. - Go to Data Window - Click on Variable View in bottom left corner - Click on Values cell in row for age_rc, the new variable you just created - Enter the value 1 - In value label, enter 18 to 24 - Click Add button - Repeat for ranges 25 to 34, 35 to 44, 45 to 64 5) Computing a new variable. - Go to Transform, Compute - In target variable, type in the name of a new variable in this case age_sq - In the larger box, type age*age -- this command will create a variable called age_sq which is the age of the respondent squared

3 p. 3 6) Saving a data file. - Go to File, Save As - Select the proper folder and save the file under a different name - Click Save 7) Displaying the variables in your file. - Go to File, New, Syntax - In the new syntax window, type display. the period is very important - Highlight the text and click on the play button at the top of the syntax window - A list of the variables in your file will appear Basic Descriptives in SPSS 1) Basic frequency table - For the first table, go to Analyze, Descriptive Statistics, Frequencies - Click on race and hit the arrow button to put race into the variables column -Click on lesshs and hit the arrow button to put race into the variables column - Hit OK 2) Using the Frequency command to create descriptive statistics - Go to Analyze, Descriptive Statistics, Frequencies the race and lesshs variables should still be present - Click on the Statistics button - Select mean, median, minimum, maximum, and standard deviation - Hit Continue - Uncheck the box marked Display Frequency Tables - Hit OK

4 p. 4 3) Using the Descriptives command - Go to Analyze, Descriptive Statistics, Descriptives - Click on race and hit the arrow button to put race into the variables column - Click on lesshs and hit the arrow button to put race into the variables column - Hit OK Examining Basic Descriptive Relationships in SPSS 1) Creating a scatterplot of two variables. - Go to Graph, Scatter - Make sure Simple is highlighted, click Define - Select jobacc for the X-axis and ann_earn for the Y-axis 2) Creating a two variable cross-tabulation. - Select race for the row variable and auto for the column variable 3) Creating a two variable cross-tabulation with row and or column percentages. - Select age_rc for the row variable and lesshs for the column variable - Click on cells, select row percentages - Click Continue, click OK - Your variables should still be in the row and column places - Click on cells, select column percentages - Click Continue, click OK 4) Creating a three variable cross-tabulation.

5 p. 5 - Select auto for the row variable and lesshs for the column variable - Select race for the Layer variable - If you would like click on cells and select row/column percentages - Click Continue, click OK - SPSS produces a table that sorts respondents by race and auto, then looks at education 5) Creating a correlation matrix between three variables. - Go to Analyze, Correlate, Bivariate - Select jobacc, ptmwork, and ann_earn Selecting and Sorting Data in SPSS 1) Selecting cases that meet a certain requirement. - Go to Data, Select Cases - Click on If condition is satisfied - Click If - Select age and click over to large window - Click the less than button (<) and type in 45 this will select cases where the respondent is less than 45 years old - Click Continue - Be sure that at the bottom of the dialog window, that the button for unselected cases is marked for filtered this is very important you will notice SPSS creates a new filter variable titled filter_$ at the end of the file you can rename this variable and make it a permanent part of the data set *You will notice that a filter on note is posted at the bottom of the data window - To unselect go to Data, Select Cases - Choose All Cases and Click OK this will remove the filter based on the criterion you chose 2) Splitting a data file along a certain criteria. - Go to Data, Split File

6 p. 6 - Select Compare Groups - Click race into the groups based on box now all your analyses will be conducted separately for whites and blacks *You will notice that a split file on note is posted at the bottom of the data window -Create a two variable cross-tabulation with lesshs and auto - To unsplit go to Data, Split File - Choose analyze all cases and Click OK this will remove the file split 3) Sorting data by a certain variable. - Go to Data, Sort Cases - Click on ann_earn and move it over to the box Click OK - If ascending order is checked, your file will be sorted by ann_earn from lowest to highest - If descending order is checked, your file will be sorted by ann_earn from highest to lowest - Note that missing values will be sorted ahead of the lowest valid value Basic Regression in SPSS 1) Basic Bivariate Regression - Go to Analyze, Regression, Linear - click ann_earn into the dependent variable box this is what we are trying to model or explain - click lesshs into the independent variable box this is a factor we think causes observed values of ann_earn

7 p. 7 2) Basic Mulitvariate Regression. - Go to Analyze, Regression, Linear - click ann_earn into the dependent variable box - click race, kids, and lesshs into the independent variable box these are 3 factors we think causes observed values of ann_earn 3) Saving and Plotting Residuals. - Go to Analyze, Regression, Linear - click ann_earn into the dependent variable box - click race, age, kids, and lesshs into the independent variable box these are 3 factors we think causes observed values of ann_earn - click Save - click Unstandardized Residuals - Go to Data Window, res_1 should appear - Go to Graph, Scatter - Make sure Simple is highlighted, click Define - Select age for the X-axis and res_1 for the Y-axis