ICP-Africa Regional Workshop
Pretoria, South Africa
20 - 24 June 2011
Validation at country level
Outline
Introduction to the Household
Consumption Survey
Intra-country data validation
Specificities with the Household
Consumption Survey
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Introduction
to
Household Consumption Survey
Categories covered by the Household Consumption Survey
Category
Food and non-alcoholic beverages
Alcohol beverages, tobacco and narcotics
Clothing and footwear
Housing, water, electricity, gas and other
fuels
Furnishing, household equipment and
routine maintenance of the house
Health
Transport
Communication
Recreation and culture
Restaurants and hotels
Miscellaneous goods and service
Global Core List
Number
of BHs Number of items
Share, %
29
189
31
4
16
3
5
53
9
5
16
3
13
75
12
6
9
3
10
2
6
92
64
64
13
53
28
30
601
11
11
2
9
5
5
100
3
Introduction
to
Country level validation
Intra-country validation is a stage carried out by the
NCAs to establish that
1
2
3
Reported prices are correct
Price collectors within a country have priced products that
match the product specifications
Survey frame worked as anticipated
Validation stage for items on regional item lists
Quarterly Data
Annual Data
National and subnational
4
Validation phases
intra-country validation
1st Phase: Initial
Data
within
Data Validation for Quarterly and Annual
Objective to initially check price data collected by price collectors
2nd Phase: Statistical
test for Quarterly and Annual Data
Objective to study and correct the data using statistical means
3rd Phase: Finalization
Data
of data for Quarterly and Annual
Objective to finalize the data and to send it to RCAs
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1st Phase intra-country
Initial Data Validation
Step1 Add price and metadata to validation software
• Ensure that the data is in right format
Step2 Check prices and metadata for errors and discrepancies
• Prices seem initially plausible and are according to NCA’s knowledge of the market?
• Priced products are according to products specifications?
• Quantities are correctly reported and calculated?
Step3 Check that prices are sub-nationally plausible
• Price differences between the regions/cities within a country are plausible?
Step4 Check that prices are temporally plausible
• Prices are plausible vis-à-vis previous ICP round or previous quarters?
Step5 Check the number of important items
• Minimum requirement is1 important item per BH
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2nd Phase intra-country
Statistical Tests
Individual prices (price-observation-table)
Step1 Check prices using Deviation test
• Measures deviation of the reference-quantity price for a price
observation to the average reference-quantity price for the product
Step2 Check prices using T-Ratio test
• Compares individual price observations’ deviation from the average price
against standard deviation of the product in reference quantity
Average product prices (average-observation-table)
Step3 Check prices using Min/Max-price-Ratio test
• Compares minimum price against maximum price in reference quantity for the product
Step4 Check prices using Coefficient-of-Variation test
• Standard deviation expressed as a % of the av. price for the product
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3rd Phase intra-country
Finalization of data
Step1 Confirm prices and metadata to be intra-country validated
• Ensure that all steps have been carried out successfully
• Ensure that data is in right (pre-agreed) format
Step2 Submit prices and metadata to RCA
Note:
After receiving the data, RCAs may discover problems with the data
• Naturally this should be corrected instantly and before inter-country validation starts
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Specificities
with
Household Consumption Survey
Validation checks for all items
Individual countries Priced products are according to the item specifications ,
survey frame is realistic for the item in question?
Countries within region Price data is comparable?
Food and non-alcoholic beverages
Quantities Reference quantities are correct (especially with multipack items),
priced products fall into requested quantity range?
Generic items Priced products are comparable brand wise? How are the
private labels (SOBs) categorized?
Alcohol beverages, tobacco and narcotics
Black market products Priced or not?
Clothing and footwear
Generic items Priced products are comparable brand wise? How are the
private labels (SOBs) categorized?
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Specificities
with
Household Consumption Survey
Housing, water, electricity, gas and other fuels
Quantities Correctly calculated?
Price volatility Comparability?
Furnishing, household equipment and routine maintenance of the house
Generic items Priced products are comparable brand and model wise?
Technical parameters Prices are comparable?
Note Splittings, method for fast evolving technological products
Health
Pharmaceuticals Correct quantities, comparable active substances and brand
types (generic, original)?
Services Comparable facilities priced? How is government compensation
treated?
Transport
Fuels Price volatility, comparability of prices?
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Specificities
with
Household Consumption Survey
Communications
Services Comparability of various “deals”?
Recreation and culture
Services Comparability?
Restaurants and hotels
Quality Comparability of priced services?
Miscellaneous Goods and Services
Quality Comparability of priced services?
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THANK YOU
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