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GLOBAL ADULT TOBACCO SURVEY (GATS) IN TURKEY Yılmaz ERŞAHİN Methodology Department

GLOBAL ADULT TOBACCO SURVEY (GATS) IN TURKEY Yılmaz ERŞAHİN Methodology Department Sampling and Quality Techniques Group Team Leader of Household Survey Methods. OVERVIEW OF THE PRESENTATION. Finalization of The GATS Sampling Design Sample Selection Coverage Estimation Level

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GLOBAL ADULT TOBACCO SURVEY (GATS) IN TURKEY Yılmaz ERŞAHİN Methodology Department

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  1. GLOBAL ADULT TOBACCO SURVEY (GATS) IN TURKEY Yılmaz ERŞAHİN Methodology Department Sampling and Quality Techniques Group Team Leader of Household Survey Methods

  2. OVERVIEW OF THE PRESENTATION • Finalization of The GATS Sampling Design • Sample Selection • Coverage • Estimation Level • Address Frame • Sample Size • Sampling Method • Sampling Units • Stratification Criterion • Sampling Distribution • Response/Nonresponse Rates • Weighting

  3. Finalization of The GATS Sampling Design GATS sample design was prepared appropriately by GATSSample Design Manual and then revised in accordance with the committee's questions. Sampling design was explained in the workshop with National Tobacco Experts and Second Technical Mission (September 25-26, 2008) in TURKSTAT. GATS sampling design was finalized after the workshop.

  4. SAMPLE SELECTION Coverage All households in Türkiye borders were covered. Thepopulation defined as institutional (population living in dormitories, hospitals, jails, rest homes and soldiers) are out of coverage. And also the villages which have population less than 200 were not covered in the survey as these villages involve small number of households and hence they do not allow reaching the sufficient block size. Estimation Level Sample size of the survey is calculated to do estimations on the base of total of Türkiye.

  5. SAMPLE SELECTION Address Frame The frame used in sampling studies of survey is the National Address Database (September 2008) which is the base of 2007 Address Based Population Registry System. Sample Size Since the GATS Sample Design Manual requires at least 8000 respondent questionnaires by allocating, 4000 respondent per each region (urban/rural) and in each region 2000 males and 2000 females are to be guaranteed. By the use of 2006 Türkiye Time Use Survey results, the total sample size calculated as 11200 households. Total sample size of 400 blocks (each has 28 household addresses) was equally allocated to the areas (urban / rural) so that each area have 200 blocks.

  6. SAMPLE SELECTION Sampling Method The sample design of the survey is 3 staged stratified systematic cluster sampling method. Primary Sampling Units (Psu): Clusters In all urban areas the frame is divided into clusters of approximately 300 households each. These were selected with equal probability using systematic sampling. The same procedure was applied to rural areas where localities have been divided into clusters.

  7. SAMPLE SELECTION Villages with PPS: Villages with population 200 and below were excluded from the frame because of insufficient sample size. And then remaining villages data was partitioned two part. Villages with population greater than 201 and lower than 500 is the firs part, and villages with population greater than 501 and over is the second part. In the firs part data, villages were sorted in ascending order by population and then minimum and maximum populated villages combined two by two based on cities. This procedure was done systematically. Villages were selected with probability proportional to size (PPS).

  8. SAMPLE SELECTION Secondary Sampiling Units (Ssu): In the second stage, sample households were chosen from the selected clusters (blocks) using systematic selection method. In this stage, totally 28 households were chosen systematically in each cluster and then households were divided into 2 equal size of groups as ‘female households’ and ‘male households’ randomly. Thus, in each cluster 14 male households and 14 female households involved. Final Stage of Sampling In the last stage, by using Kish Table one individual will be selected within the selected each household related with male or female household. This procedure will be done by IPAQs.

  9. SAMPLE SELECTION Stratification Criterion Settlements with population 20.000 and below classified as rural, and with population 20.001 and over classified as urban. Sampling Distribution The total sample size is 11 200 households. 400 Clusters (blocks) constitute the sample. 200 of these selected clusters (blocks) were chosen from urban areas and other 200 clusters (blocks) were chosen from rural areas. Since non-response is also taken account, substitution will not be used in survey.

  10. RESPONSE/NONRESPONSE RATES (HOUSEHOLD)

  11. RESPONSE/NONRESPONSE RATES (INDIVIDUAL)

  12. WEIGHTING Since selection probabilities are used according to the data set obtained from sampling, weighting procedures will be done. Determined final weight will be composed of several factors mentioned in the manual: 1- Computing the base weights for each sample respondent, 2- Adjusting the base weights for nonresponse, 3- Calibrating the adjusted weights to known population totals.

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