Disposition of the IFPS II Sample on the Postnatal Questionnaires

DispositionMonthTotal Birth Screener-Month 12d
Total mailed, na309630453021300829822970293929022850
Disqualified from mailing list after questionnaires were mailed, n222025212837364748
    Undeliverable, n9917202836354648144
    Accidentally dropped from sample, n21101110169
    Gulf Coast hurricane zip code, nb1111700000081
Adjusted total mailed, n307430252996298729542933290328552802
Disqualified, n200200000554c
    Infant died, n10000000011
    Long-term illness, n10020000029
Refused, n15247131125094
Not returned, n5196327567988529009481022995
Complete and qualified, n255223882238218320952020194418081807
Response rate: (No. of surveys completed/adjusted No. mailed − No. of women disqualified), %83.178.974.773.170.968.967.063.364.5
  • a The number of questionnaires mailed decreased slightly across the months because of disqualifications on earlier questionnaires. However, the questionnaires were mailed so close in time to each other that sometimes the subjects who disqualified could not be removed from the sample before the next mailing. Therefore, some subjects who did not qualify were mailed questionnaires each month.

  • b Sample members were excluded from the remainder of the study if they resided in the zip codes to which the US Postal Service stopped delivery as a result of the 2005 Gulf Coast hurricanes.

  • c Includes all disqualification categories, beginning with the birth screener.

  • d The total number includes cases from the Birth Screener and the Neonatal Questionnaire as listed in Table 1.