THE REVISED CONSUMER PRICE INDEX IN ZAMBIA

Transcription

1 THE REVISED CONSUMER PRICE INDEX IN ZAMBIA Submitted by the Central Statistical office of Zambia Abstract This aer discusses the Revised Consumer Price Index (CPI) in Zambia, based on revised weights, new methodology and software for data rocessing. The aer also highlights the differences between the old and revised Consumer Price Index (CPI). This aer has been reared by Mr Philli Miti, Central Statistical Office, Zambia. 1 of 10

2 I. Introduction 1. The Consumer Price Index (CPI) measures changes in the average level of retail rices of goods and services urchased by tyical households for the urose of consumtion. The CPI is a key macro-economic indicator. Consequently, it is of great interest to government, labour unions, business organisations, research Institutions and the general ublic. In Zambia, the CPI is mainly used by the central bank and the government as an imortant fiscal and monetary tool. 2. The Central Statistical office recently launched the revised Consumer Price Index, based on a new methodology and software for data rocessing. In the rocess of revising the Consumer Price Index, technical assistance was sought from both the International Labour Organisation (ILO) and International Monetary Fund (IMF). Scoe and Coverage 3. The revised CPI covers non-institutionalised rivate households residing in both rural and urban areas of Zambia. All the 10 rovinces and 56 districts are covered. Prices of 438 goods and services are collected from a samle of retail and service outlets. II. Background 4. The first series of the Consumer Price Index in Zambia was for urban households with an index reference eriod of The index was comiled and ublished according to the High Income Wage Earners and Low Income Wage Earners. 5. In 1997/1975 a full scale household budget survey was conducted and rovided the basis for revising the weights for the Consumer Price Index. The survey covered rural as well as urban areas. However, the weights were comuted from the exenditure rofiles of urban households only. Price collection was restricted to urban areas along the line of rail and hence the CPI reflected changes in urban retail rices only. 6. By the early 1990 s the Government recognised the need to have a national index that was reresentative of the whole country and that would reflect current sending atterns of the oulation. In view of this, a rovision was made to carry out a comrehensive house hold budget survey in 1993/ of 10

3 7. The 1993/1994 Household Budget Survey covered the whole country on a samle basis. A samle of 1800 households was selected. The overriding objective of the survey was to roduce the weights for the new CPI and after consultation with users, it was agreed that three retail rice indices were required, these would be for: (a) Urban uer-income households (to 20% by income); (b) Urban lower income households (lower 80% by income): and (c) Rural households 8. With this requirement it was aroriate to stratify the country in to two strata. The first, comrising the 10 major towns was designated Metroolitan. The second comrising the small towns and the rural was called Non- Metroolitan. The major towns included Livingstone, Lusaka urban, Kabwe urban and all Coerbelt towns. The Metroolitan stratum was further stratified into urban uer-income households and urban lower-income households. This means that the major towns comrised the indices for Metroolitan high income and Metroolitan low income grous, while the small towns and rural areas formed the Non- Metroolitan grou. 9. U to 1991, the selection of outlets to rovide rice quotations for the consumer rice index was restricted to urban areas along the line of rail. In 1991, the selection was broadened to include outlets from districts in every rovince of Zambia. The range of outlets was also broadened to include oen markets. 10. Another comrehensive Household Budget Survey (HBS) was conducted in 2002/2003 and this rovided the basis for revising the weights for the current Consumer Price Index (CPI). The weights were rice-udated to 2009, the index reference eriod. III. 2002/2003 Household Budget Survey 11. The survey covered 520 Standard Enumeration Areas (SEA s) or aroximately 10,000 non-institutionalised rivate households residing in both rural and urban areas of all the 10 rovinces in Zambia. The survey was carried out for a eriod of 12 months using a rolling samle. The 360 days in a year were divided into 10 cycles of 36 days each and 52 SEA s, which is one-tenth of the 520 SEA s, were covered every cycle countrywide. 3 of 10

4 Classification 12. The revised Consumer Price index has adoted the Classification of Individual Consumtion by Purose (COICOP). Weights 13. The weights for the revised Consumer Price index were derived from the 2002/2003 Household Budget Survey, and rice-udated to 2009, the index reference eriod. The weights are based on household final monetary consumtion exenditure. With the weighting system develoed for Zambia, both horizontal and vertical aggregation is ossible, e.g., the National all-items CPI resulting from the aggregation of the regional all-items CPIs is equal to the all-items CPI obtained from aggregating the national rice relatives for individual roducts. Division weights by rovince are shown below: Division Table 1: Division level weights by Province Central Coer belt Eastern Luaula Lusaka Northern North western Southern Western Total 1. Food and non-alcoholic beverages Alcoholic beverages & tobacco Clothing and footwear Housing, water, electricity, gas and other fuels Furniture, household equiment and maintenance Health Transort Communication Recreation and Culture Education Restaurant and hotesl Miscellaneous goods and services Total Key features of the revised CPI: 14. Summarised features are as follow: (a) A revised basket of goods and services comrising 438 roducts. (b) Classification of Individual Consumtion by Purose (COICOP) (c) New exenditure weights from the 2002/2003 Living Conditions Monitoring Survey (LCMS) (d) A new index reference eriod 2009=100 4 of 10

5 (e) Use of Geometric Mean in calculating elementary level indices (f) Comilation of rovincial Indices (g) Exanded scoe (number of districts and outlets) (h) New comuter system for data entry and data rocessing 15. The differences between the Old and the Revised CPI are summarized below: Table 2 - Comarison of the Old and revised Consumer Price Index Item/ Area Old CPI Revised CPI Basket of roducts Classification system 8 Divisions 12 Divisions Exenditure weights Comiled according to: (COICOP) Derived from 1993/1994 Household Derived from 2002/2003 LCMS III Budget Survey (HBS) HBS tye Metroolitan Low Income Grou, Provincial CPIs Metroolitan High Income Grou, and Non-Metroolitan Grou Index reference eriod (Base Period) Methodology for calculating Arithmetic mean of rice elementary aggregates relatives(ar)-carli index Methodology for calculating Laseyres tye formula (direct uer-level aggregates method) Price quotations er month 15,000 30,000 Districts 45 All districts in Zambia Outlets ,000 Software for Data Entry, Processing and Reorting Dbase IV, DOS based Features of the New CPI Software The ratio of geometric mean of rices (GM)- Jevons index Laseyres tye formula (chained index) Microsoft Access, with Visual Basic for Alications (Windows based) 16. The New CPI System has been develoed in Access with the following features: - (a)uses Windows latform (b)proagates centrally collected rices to rovincial outlets (c)validation is immediate, which allows immediate correction (d)editing/ reviewing of quotations is flexible ermitting filtering of records of interest such as the threshold (uer and lower limits) values of rice change rates (e)prints Questionnaires from the alication (f)system works in a Client-Server environment, suorting a minimum of 5 of 10

6 15 users concurrently (g)system is secure (imlements log-on and roles) IV. Formula Calculation of the elementary aggregate rice indices 17. The ratio of geometric mean of rices formula is used in constructing elementary aggregate indices. The formula has many desirable mathematical roerties and roduces unbiased results. The formula is exressed algebraically as follows: I 0: t J n i1 t i 0 i 1 n where t i is the rice of roduct i in month t. 0 i, j is the reference eriod rice of roduct i in month 0. Calculation of uer-level indices 18. Laseyres tye arithmetic mean formula for higher level aggregation is used, in a chained form. The national index is calculated in two stes. (a) Class/Grou/Division/All items indices at rovince level are calculated as weighted averages of the indices for elementary aggregates according to the following formula: n I t/0= w i=1 0, i * ( t,i 0, i ) where I t / 0 is an index for all roducts showing the average change between eriod 0 and t. t, i is the rice of roduct i in a month t. 6 of 10

7 0,i is the base eriod rice of roduct i in a month 0. w 0,i is the rovincial weight of roduct i (b) These rovincial indices (at the Class/Grou/Division/All items level) are then further combined to estimated indices at the national level. The national indices are calculated as a weighted averages of rovincial indices by using regional weights. The formula is as follows: I N t / 0 = 9 P=1 g P 0 9 P=1 * g P 0 I, P t / 0 P It / 0 is a rovincial index for class/grou/division/all items showing the average change between eriod 0 and t. P g 0 is the regional weight. N It / 0 is a National index for class/grou/division/all items showing the average change between eriod 0 and t. V. PRICE COLLECTION Data Collection Instrument 19. Prices are collected from outlets using the Consumer Price Index Questionnaire. It has information about the resonding outlet, the resonse month, and details of roducts quoted that is roduct code, roduct descrition, and rice. Data collection time-table 20. The rice collection eriod is from 1 st to 10 th of every month. The CPI statistical bulletin is released the last Thursday of the reference month. 7 of 10

8 Frequency of rice collection 21. Prices of all the goods and services used to comile the CPI are collected once er month. Central or Head Office Price Collection 22. Centrally collected rices include the following :- (a) Charges of ublic utilities or services rovided by deregulated (or regulated) bodies or Government (such as electricity tariffs, bus and train fares, ostal services, telehone services etc.) (b) Taxes and license fees aid to Government (for examle, television license and vehicle license) Local Price Collection 23. For many items, rices are collected locally by data collectors based in all the 9 rovinces by visiting retail outlets and recording current rices for the samle of goods and services. House Rent Survey 24. A samle of housing units are surveyed every month to collect house rental data. A samle of 100 housing units are covered from each rovince excet for Lusaka and the Coerbelt with samles of 300 housing units each. The housing units have been stratified into Low cost, Medium cost and High cost. VI. Problems CPI basket/weights revision 25. One of the roblem encountered in comiling the CPI is the outdated weights and basket of goods and services. The 2003 ILO resolution on Consumer Price Indices states that weights should be revised at least once every 5 years. The revision of weight and basket deend on how often the Household Budget Survey is undertaken. The revious HBS s were conducted during the eriod: 1974/1975, 1993/1994, 2002/ of 10

9 Price u-dating of weights 26. The current CPI exenditure weights were derived from the 2002/2003 HBS, and having chosen 2009 as the rice reference eriod, the weights were rice u-dated to Price u-dating was alied at the roduct level, where each exenditure weight was multilied by its corresonding roduct index. However, since in the old basket had 357 roducts comared to 438 in the new basket, roduct indices for 81 roducts had to be estimated. Outlet selection 27. Non-random (urosive aroach) is emloyed in selecting outlets. For examle, outlets that are selected are those most frequented by the households. Generally, available information and alication of best judgement was used to ensure that reresentative samles are selected. When an outlet has closed ermanently, it is usually relaced with a similar outlet not too far from the one which closed down. Prices for non-standardised quantities 28. Food items that are sold in non-standard quantities are usually found in markets and these include fresh food (vegetables etc.), dried vegetables, cereals etc., The collector takes a weighing scale to the market for uroses of weighing bundle or hea or contents of a late or cu which is then converted to a rice er Kg. The collectors record the rice of the reorted quantity, and the conversion is done in the office by comilers. Prices for clothing, furniture and electrical aliances 29. Many roblems are encountered in the collection of rices for roducts such as furniture, clothing and household aliances. This is due to frequent changes in roduct secifications. Temorary missing roducts 30. When a roduct is temorary unavailable, the current rice is estimated using the monthly rice change in rices of the set of roducts in the same COICOP class (short-run geometric mean imutation). Permanently missing roduct 31. When a roduct becomes ermanently unavailable, a close substitute is selected. The use of a chained index makes the estimation of missing rices and 9 of 10

10 introduction of relacements easier: a relacement is included in the index as soon as rices for two successive months are available. Seasonal roducts 32. The missing rices for the strongly seasonal roducts are estimated as in the case of temorary missing roducts. Data validation 33. he manual editing is done both in the field and in the office before data entry. Comuter editing is done as follows: VII. (a) At Head quarters, rices from Consumer Price Questionnaires are entered on to the system on client PCs. (b) During data entry the system comares the quoted rice against the revious month's rice to ensure that the new rice is within the accetable range. (c) Editing of rices the system comutes variance attributes based on roduct s revious month s rice, and the month's quoted rice. In editing, variances rovide the means of identifying otential roblem entries, such as where a quotation might be way out of the exected rice (d) Correction of quotations where roblems are identified, a reference may be made to the hysical rice quotation (questionnaire), or where the officer erforming the editing may use emirical knowledge of the roduct. In all cases the rice can be amended to reflect the value deemed to be correct Future Revisions 34. The next revision of the Consumer Price Index deends on the conduct of the HBS. The last HBS was carried out in 2002/2003, and with a time lag of this imlies that the current weights may not adequately reflect the sending atterns of the oulation. Consequently, there is need to revise the CPI at least every 5 years. VIII. Conclusion 35. The discussion in this aer attemts to resent the various features of the revised consumer rice index(cpi). Most significant are changes in the method used in calculating elementary aggregate indices and the software for rocessing the CPI. 10 of 10