About the first wave of the survey (JHPS2009)

The first wave of the survey (1st wave)

- Coverage of the Survey

Males and females aged between 20 years and over as of 31 January 2009.
(Males and females born before January 1989).
According to the population estimates for February 2009, there were 103.61 million people in this group and it constituted 81.5% of the total population of Japan.

- Survey Date

The survey was implemented on 31 January 2009.

- Selection of survey respondents

1. (1) Sample Size
   4,000 People (the data include an extra 22 individuals who were surveyed as a back-up sample)
2. (2) Method for Sampling
   Two-stage stratified sampling (1st stage: survey area, 2nd stage: individual)
3. (3) Selection of areas surveyed
   Census enumeration districts for the 2005 National Census were used as the survey areas.
   First, the whole country was stratified into 24 strata by region and city class, and then, the sample size for each stratum was determined by each stratum’s share of the population based on the National Residents Register as of March 31, 2008.
   Next, survey areas in each stratum were selected at random. The number of survey areas was determined for each stratum based on the assumption that approximately 10 people would be selected to be surveyed in each area.

Details of the allocation of the sample across regions and city class

	18 Large Cities	Other Cities	Towns and Villages	Total
Hokkaido	60	82	34	176
Tohoku	32	104	60	300
Kanto	498	742	76	1,316
Chubu	142	510	82	734
Kinki	200	408	40	648
Chugoku	36	182	22	240
Shikoku	-	108	22	130
Kyushu	74	310	72	456
Total	1,042	2,550	408	4,000

4. (4) Selection of Survey Respondents
   For each survey area, approximately 10 people were selected to be surveyed based on the National Residents Register. Selected respondents were restricted to eligible individuals. As for the detail of selection process, from a certain point on the National Residents Register, individuals listed were selected using a fixed interval.
   
5. (5) Choice of the back-up Sample
   In order to obtain a sample of 4000 individuals, if an individual originally selected did not take part in the survey, s/he was replaced by an individual who had previously been selected as a back-up sample. The back-up sample was selected to have the same sex (male or female), and the same age grouping (in their 20s, in their 30s, in their 40s, in their 50s, in their 60s or over) as the original individual.

- Survey Method

Survey areas were randomly divided into two parts (denoted Group A and Group B), and two different survey methods were applied.

• Group A
  The survey was implemented by the drop-off pick-up (DOPU) method. The surveyor distributed the questionnaire to the survey respondent, and later the surveyor revisited the respondent to collect the questionnaire that had been completed by the respondent. For this group, the survey is totally self-administered.
• Group B
  The survey was implemented by the drop-off pick-up (DOPU) method plus interview method. The surveyor distributed the questionnaire to the survey respondent. The survey questions were divided into two parts, with one part is organized as an interview ?the surveyor asked questions to respondents in person. The other part is self-administered, and the surveyor revisited the respondent to collect the questionnaire which filled by the respondent her/himself.

In addition to these two methods, all respondents were offered the option of answering using a web-based answering option.

■ 1st wave (JHPS2009) questionnaire PDF