Survey ID Number
KIR_2006_HIES_v01_M
Title
Household Income and Expenditure Survey 2006
Sampling Procedure
Sample Size
In determining an appropriate sample size for a survey of this nature, numerous factors come into the equation. These include:
a) The degree of accuracy required for key estimates
b) The population size of the country
c) The manner in which the sample is selected
d) Cost or staffing constraints which may exist
e) Whether or not estimates are required for sub-populations
f) The level of variability in the data being collected
Each of these factors have different magnitudes of importance, but the major priority should always be on selecting a sample big enough to produce results of suitable accuracy. Many of these issues are generally known as well - for instance:
· A user group may pre-specify what level of accuracy they may wish to achieve for the survey
· The population of a country can normally be estimated to a reasonable level of accuracy
· The sample selection technique adopted is known
· Cost and staff constraints are generally known, and
· A user group can once again provide information on whether estimates for sub-populations are required.
The one thing that normally isn't known is the degree of variability in the data being collected - this information comes after the survey. This factor is important because if there is not much variability in the data for key estimates, then the sample size does not need to be as large, and vice versa.
Without this sort of information, determining the appropriate sample size for a survey can often involve a bit of guess work. For that reason, based on previous survey experience in other Pacific Island countries, a sample of 10 per cent was considered more than sufficient for Kiribati. An additional 10 per cent of sample was selected to allow for sample loss.
As a result, a sample size of 1,555 households (10 per cent of 13,999, with a 10 per cent top-up) was considered suitable for the survey.
Allocation to "Target Areas"
For the Kiribati HIES, five target areas were identified as sub-populations for which estimates would be desirable. These five areas were:
1) South Tarawa
2) Northern Gilbert
3) Central Gilbert
4) Southern Gilbert
5) Line/Phoenix Islands
Once the sample size of 1,555 had been determined, the next step was determining how the sample should be allocated to each of these target areas in order to produce the required level of accuracy for each area. In order to achieve this, the sample was allocated in such a manner that the expected level of accuracy for each stratum would be similar. The resulting sample allocation can be found in the table below.
Stratification
To achieve better representation within each target group, each target group was further stratified by grouping "like" islands. The plan from there was to select an island from each stratum to represent it. As a result, 11 strata were formed, with each of the 23 populated island/atolls of Kiribati allocated to one of these strata. The resulting strata, and islands which make them up, can be found in the following table.
The allocation of the sample to stratum within each target group was achieved by simply allocating the sample proportional to the population for that stratum. For example, for the target group Northern Gilbert, an overall sample size of 323 was desirable. To determine how much of that sample would be allocated to the first stratum which consisted of Makin and Butaritari, the following formula was applied:
n (Makin & Butaritari)= 323 * (889)/(889+1290+867)= 94
Excluded Areas
Although it would be desirable to cover all of Kiribati for this survey, due to cost and time constraints a couple of areas were excluded from the frame before the selections were made. The two areas removed from scope were:
· Banaba
· Kanton
The impact on final estimates is considered to be very small given the small populations on these two islands; 61 households on Banaba, and 9 households on Kanton. This accounts for about 0.5 per cent of the population of Kiribati.
Sample Selection Technique
Selection of Islands
For the stratum with more than one island, an island had to be selected in order to represent that stratum. The process used for this stage of selection was probability proportional to size (pps) sampling, where the size measure was the number of households on the island.
An example of how this process worked can be found below for the Central Gilbert - Group 2. For this stratum, a random number was selected between 0 and 1,005. Given the random number (254), fell within the cumulative number of households for Abemama, then that island was selected.
Selection of Households
To minimize the travel requirements of interviewers, and thus travel costs, a two stage process was adopted to selected households.
The first stage of the process involved selecting EAs using probability proportional to size (pps) sampling. The required number of EAs to select from each island was simply determined by dividing the number of households to sample on that island by roughly 15, where 15 was the cluster size chosen from each selected EA.
Having selected the EAs in sample, a systematic skip was run through the list of households for each EA to determine which households would be selected in sample. These selections were performed in the NSO, and the lists provided to interviewers in the field. The lists used for this stage of selection were based on the 2005 Population Census, and thus would be out-of-date by a year or so, but given the significant gains in simplifying field logistics, this was the preferred option.
Questionnaires
Household Control Form
The Household Control Form (HCF) should be filled in during the first visit to the household. Its main objective is to collect basic demographic information about members of the household. Before completing this form however, the interviewer needs to determine if the household is in scope for the survey.
Only those households which have been residing in Kiribati for more than 1 year, or those households who intend to reside in Kiribati for a total of 12 months or more, should complete this form and partake in the survey. These households can be identified by going through section (e) in the field book for interviewers. If the household does not meet these criteria, then the survey is over. In assessing the eligibility of a household to be in the survey, use some common sense - there will be many occasions when it will be clear that the household has always lived in Kiribati, so don't bother asking these questions.
Once this issue has been addressed, the HCF can be filled in for the household. The HCF form is to record names of all the usual members of the household. Information on relationship to head of household, sex, date of birth and ethnicity are asked of all members in the household. For persons aged 15 and over, questions on marital status, educational attainment, activity status, literacy status and internet usage are also asked. Codes should be used to complete these questions, and they can be found in the interviewer's field book in section (a). You must enter the code for these questions.
Expenditure questionnaire
The purpose of this questionnaire is to record household expenditure that is not included in the diary. There are some big purchases that the household may only make once or twice a year. Also the household may make regular payments, which may not be done during the survey period, and we would need to know such payments to produce good and complete estimates.
There are 15 sections in the Expenditure Questionnaire which relate to the following:
1. Dwelling tenure; 2. Mortgages and loans for purchase of dwellings; 3. Insurance policies; 4. Construction of new dwellings; 5. Major home improvement; 6. Household operations; 7. Transportation; 8. Overseas and domestic travel; 9. Education, recreation, sport and culture; 10. Loans; 11. Contribution to benefit schemes; 12. Medical and health services; 13. Miscellaneous payments; 14. Agricultural assets
Detailed instructions for each section are not provided here as they can be found in the questionnaire itself on the left hand side of the booklet.
Income questionnaire
This questionnaire is to record the household's total income received or earned in the last 12 months. Information will be collected for all usual members of the household who are 15 years and over. Visitors are not to include their income earned in this section.
There are 7 sections in the Income Questionnaire which relate to the following:
1. Working for wage and/or salary; 2. Agriculture, livestock, fishing and other sales; 3. Other self employed and business operations; 4. Previous jobs held in the last 12 months; 5. Services provided to other private households; 6. Welfare benefits/allowances; 7. Other income, including remittances
Detailed instructions for each section are not provided here as they can be found in the questionnaire itself on the left hand side of the booklet.
Weekly Diary
For each household observed, there will be two books, one for the first week and one for the second week. This is to keep a record of all daily expenditure for the 14 days. Interviewers have to make sure that these diaries are being kept for each day. Instructions on how to use the diary have been written on the front pages of these diaries.
In normal circumstances, the head of household organises the household activity. In some households this may not be the case - some members of that particular household may not be seeking the authority of the head when some expenditure is encountered. This situation may result in not recording all expenditure in the diary. The interviewer should discuss the matter with the head of the household to ensure that each member's expenditure is recorded in the household diary. If a member of the household does not co-operate with the head of the household he/she may be allocated a separate diary. That member of the household should be explained the full responsibility of recording the diary.
There are 4 main sections making up each weekly diary:
1) Items bought; 2) Consumption of home produced commodities; 3) Gifts of cash or goods; 4) Winnings from gambling
In general, ask the household head to make a note of any problems encountered in filling out this diary. The interviewer can then address these issues upon their next visit.
Items bought
This is the first section for each day's entry, and is used for recording all items bought in a store, street vendor, or any other place. Each household is required to write down everything they bought, whether paid by cash, cheque or on credit. If you have not purchased anything for that day, or consumed any of your own produce, place a tick inside the circle at the top of that day's page to indicate it hasn't been missed.
Special instructions have been included for some items due to the tricky nature of recording their expenditure. These items include meals at restaurants, drinks at a bar, donations to the church, children's pocket money, etc. Encourage the household head to read through these cases before proceeding to fill out the diary each day.
Four pieces of information are required for each entry:
· Quantity bought; · Weight (if applicable); · Full description of item; · Amount paid or charged
Consumption of home produced commodities
This is the second section for each day's entry, and is used for recording all home produced commodities consumed on that day. Once again 4 pieces of information are required for each entry:
· Quantity consumed; · Weight (if applicable); · Description of item; · Cost of buying the same thing at the local shop/market
Make sure only home produced commodities are recorded in this section.
This section is generally the most under-reported section of the survey so it is extremely important to continually check with a household that this area is being filled out correctly each day. This is particularly the case in the rural areas where a large amount of consumption of home produce should be taking place.
Gifts of cash or goods
This section is located at the back of the diary and aims to collect 4 bits of information:
· Cash given away; · Goods given away; · Gifts of cash received; · Goods received
Cash given away: Includes monetary gifts given to someone outside the household. Include the day, amount, to whom it was given and where they live.
Goods given away: Includes non-monetary gifts given to someone outside the household. Include the day, quantity, weight, description of good, estimated value, to whom it was given and where they live.
Gifts of cash received: Includes monetary gifts received by a member of the household from someone outside the household. Include the day, amount, from whom it was received and where they live.
Goods received: Includes any non-monetary gift received by a member of the household from someone outside the household. Include the day, quantity, weight, description of good, estimated value, from whom it was received and where they live.
At the time when any of these transactions take place, the entry should be made in the appropriate place at the end of the diary.
Winnings from gambling
This is the final section of the diary and includes money won from any form of gambling. In the table provided, include the day, type of betting and amount won.