OTROS MEDIOS DE FAVORECER EL PRINCIPIO DE LA DEMOCRACIA

Two interviewers were trained at the beginning of April 1990. As part of their training, a pilot survey was conducted using 21 Canberra respondents from the Australian Family Project survey. The pilot test's three main objectives were to evaluate: a) the interview instrument, in particular the flow and wording of questions and reliability of responses; b) face-to-face versus telephone interviews; and c) other field procedures, including the letter of introduction, refusals and respondent migration. The major finding of the pilot survey was that telephone interviews offered more benefits than face-to-face conversations, being substantially cheaper,

requiring less time and eliminating large amounts of travel. Furthermore, they reduced the problems associated with a male interviewer^ and the presence of other household members. The main survey, therefore, first approached respondents for a telephone interview.

The main field procedures

At the end of each interview during the Australian Family Project survey in 1986-87 respondents were asked whether they were willing to participate in a future follow-up study, and to give their name, address, telephone

number and an alternate contact. Of the 441 respondents from the Sydney sample, 14 per cent refused to participate further, leaving 379 to be followed up.

The consenting women were sent an introduction letter in 1990 (see

Appendix 3.B) to either the address given at the time of the first survey or an updated address found in the telephone book. Approximately one week later contact was attempted by telephone.^ In the five per cent of cases

where telephone numbers were not available, the letter was followed up with one or more visit to the residence.

A total of 169 respondents (45%) were no longer living at their 1986-87 address. In an attempt to establish their whereabouts a hierarchical search

5 Two-thirds of the interviews were conducted by myself.

6 Batches of appropriately 50 letters were sent at one time to addresses fairly close to one another. Once the majority of these respondents had been interviewed the next 50 letters were sent. This method allowed a quick follow-up of letters and easy management of difficult areas or cases.

method was employed (see Appendix 3.C for more detail). This was the most time consuming part of the field procedures, with a considerable amount of time spent 'door knocking'. Of the 169 respondents who had moved, 64 per cent were located. Two-thirds of those found had moved within the Sydney region, while eight per cent were living in other

metropolitan areas, 17 per cent shifted to less populated areas and ten per cent were overseas. The field work took nearly seven months, starting in May 1990 and finishing in November. Seventy-five per cent of interviews, however, were completed by August, with the average time to administer the questionnaire being 30 minutes (s.d. = 13 mins).

Field outcomes

Twelve women were omitted from the sample: 11 who were overseas and one who had died. Consequently, 367 respondents were eligible to

participate. Of these women, 12 refused further involvement and 60 were unlocatable, leaving 291 who provided an interview. Thus, 95 per cent of identified women participated, with a conservative response rate of 80 per cent among those declared eligible.^ Overall, the 291 respondents yielded a conservative response rate of 45 per cent from the baseline sample. This

Q

was calculated on the basis of a 65 per cent response rate in 1986-87, an 86 per cent consent in the first survey to be followed up at a later date, and an 80 per cent response in 1990.^

Follow-up respondents were not significantly different from baseline

Sydney respondents with regard to age, birthplace, educational attainment, employment status, occupational class,^^ work history, income,^^ age first left home, marital status, marital history, household composition, number of children, timing of births, self-rated health or migration history.

Furthermore, they were demographically similar to the Census population of women living in both Sydney and metropolitan Australia

7 TTiis was a conservative estimate since a proportion of those not located would have been ineligible.

8 See footnote 3 for explanation. The response rate based on identified eligible women was 68 f>er cent.

9 Total response rate = 100 x 0.65 x 0.86 x 0.80. A less conservative estimate is 100 x 0.68 x 0.86 X 0.85 = 50%.

10 Occupational class was defined by the woman's occupation or her husband's if she was not working.

11 Income was defined as money earned from a job. There was nine per cent missing information for women, and 20 per cent missing information on spouse's income from a job. Income therefore was not used in the main analyses.

(see Appendices 3.F, 3.G and 3.H). They were, however, significantly less likely to have been renting their residence in 1986-87 than baseline Sydney respondents, with the consequence of home ownership on a follow-up response related to birthplace. For instance, living in a rented house did not substantially affect the likelihood of a follow-up response among those born in Australia, while migrants who were renting in the baseline survey were significantly less likely to have participated in 1990 = 6.7; p < 0.01,

one-sample test). The fact that a large number of these migrants could not be located in the Follow-up may indicate that some had left the country, and therefore, were not part of the target sample. Given that the combination of birthplace and home ownership is likely to be associated with health, and as a safeguard against possible biases, an interaction of these two variables is used as a control in the analyses.

Table 3.3.1 shows selected birth cohorts and their corresponding age ranges at each survey. The average time between the two surveys was three years and 11 months, with a standard deviation of 4 months.

Table 3.3.1

The age of respondents at the times of the two surveys

Age (Years)

AFPl, metropolitan Follow-up Sydney Follow-up Sydney

Approx. Australia 1986-87 1986-87 1990

birth

cohort Range Mean (s.d,) N Mean (s.d.) Range Mean (s.d.) N

1956-66 20-29 24.9 (2.8) 477 24.9 (2.8) 23-34 28.9 (2.9) 87 1946-56 30-39 34.8 (3.0) 562 34.8 (3.1) 33-44 38.8 (3.1) 97 1936-46 40-49 44.5 (3.0) 367 44.1 (3.0) 43-54 48.0 (3.0) 60 1926-36 50-59 54.8 (2.8) 272 54.8 (2.7) 53-63 58.8 (2.7) 47 1946-66 20-39 30.1 (5.7) 1039 29.9 (5.8) 23-44 33.9 (5.8) 184 1926-46 40-59 48.9 (5.8) 639 49.0 (6.1) 43-63 52.9 (6.1) 107 1926-66 20-59 37.5 (10.9) 1678 37.1 (11.0) 23-63 41.1 (11.0) 291

Despite the Follow-up respondents mostly representing the population, the small sample size may lead to imprecise estimates and reduce the power of the statistical tests to reject the null hypothesis when it is false.

Consequently, group sizes in subsequent analyses have been carefully assessed; and decisions have been made about the types of hypotheses that can be tested and the level of caution that should be associated with any results produced. In addition, a nesting procedure has been adopted to increase group size and conserve degrees of f r e e d o m .