APPENDIX - INFORMATION ABOUT THE COHORT ANALYSIS METHOD
It is important to note that Retirement and Retirement Intentions is not a longitudinal survey. That is, the survey sample is made up of different individuals in each year of the survey. By nature of the survey design and weighting methods, samples from separate years of the survey are independent from each other, and are taken to be representative of the whole age cohort. It is therefore methodologically sound to compare the sample from an age cohort in one year with the sample from the same age cohort in another year.
It should also be noted that demographic changes will occur within the population of each cohort, over the eight year period. These changes include the impact of migration and the impact of death, which may each occur at different rates within sub-populations (such as different sexes or socioeconomic groups). In addition, 'special dwellings' such as hospitals and nursing homes are excluded from the survey scope, which means part of the cohort population may move out of scope of the survey as they enter aged care facilities. Demographic changes in the population may impact on the trends discussed in this article. The 2012–13 population as a proportion of the 2004–05 population was 95% for cohort 1, 94% for cohort 2, 100% for cohort 3 and 89% for cohort 4.
Surveys are conducted throughout a financial year period, and age refers to age at time of interview. Someone who was aged 50 (for example) in the 2012–13 survey may have been born in 1962 or 1963, depending on their month of birth and month of interview. Someone born in 1965 (for example) might be captured in the survey at age 44, 45 or 46 depending on their month of birth and month of interview.