Item Nonresponse by Respondents

National Longitudinal Survey of Youth - 1979 Cohort

Item Nonresponse by Respondents

This section provides details on the amount of missing data associated with each respondent. Each table in this section shows the number of respondents who are missing data in one of the surveys. The tables are split into two parts. The left-hand part, columns one to four, shows the total number of questions that have missing data for each group of respondents. The right-hand part, columns five to nine, shows the percentage of questions that have missing data.

The top line of Table 1 shows that in the 1979 survey, 12,527 respondents never refused to answer questions. While refusals are quite rare in this survey round, don't knows and incorrect skips are quite frequent. The top line shows that only 5,084 respondents had zero don't know responses and only 2,347 respondents were sent through the entire questionnaire without any sequencing errors. Subtracting these numbers from the 12,686 total respondents means that 60 percent, or 7,602 respondents, stated they did not know the answer to at least one question and 81. 5 percent, or 10,339 respondents, were incorrectly skipped somewhere in that questionnaire.

The right-hand side of Table 1, which examines the percentage of questions missing data, shows a similar picture. Refusal rates are relatively low. There are 12,620 respondents who refused less than one percent of their questions, which means only 66 respondents refused one percent or more of the questions they were expected to answer. Thirty-five percent, or 8,185 respondents, answered don't know to less than one percent of their questions. Again, the largest group was respondents who were incorrectly skipped over questions. Only 4,313 respondents were incorrectly skipped over less than one percent of the questions, but 8,373 of the respondents were illegally skipped over one percent or more of their questions and 227 were skipped over more than 10 percent.

Refusal rates have increased steadily over time even though the more difficult respondents have presumably left the survey. Table 2, which examines the 1984 survey, shows an increase over the 1979 refusal rates. which examines the 1984 survey, shows an increase over the 1979 refusal rates. While the number of respondents answering the survey is shrinking, the number refusing to answer questions is increasing. For example, while in 1979 only 10 respondents refused to answer more than 10 questions, in 1984 there were 41 respondents. This pattern of increase is evident in Table 3, which examines 1989, through to Table 6, which examines 2004. By 2004, there were 185 respondents who refused to answer more than 10 questions.

Increasing refusal rates are also seen in the percentage side of the table. In 1979, only 66 respondents refused to answer one percent or more of the questions they were asked. This increased in subsequent surveys to 320 respondents in 1984, 355 respondents in 1989, 480 respondents in 1994, 549 respondents in 1998, and 655 respondents in 2004.

"Don't know" rates have also risen over time. In the 1979 survey, 8,185 respondents had less than one percent of their questions labeled as don't knows. This number drops in 1984 to 7,003 respondents and further drops to 6,423 in 1989 and 5,942 in 1994, 4,741 in 1998 and 3,185 in 2004. While rates have risen, relatively few individuals have high levels of don't knows. In 1979, only 68 respondents didn't know the answer to more than five percent of the questions they were asked. This number falls to 19 respondents in 1984 and then rises to 66 in 1989 before falling back to 46 respondents in 1994 and then jumps back to 66 in 1998, and ends with 149 in 2004.

While don't know and refusal rates have risen, incorrect skip problems have clearly shrunk over time. In 1979, there were only 2,347 respondents who were correctly sequenced through the entire survey. In 1984, this number rises to 7,802 respondents, followed by a rise to 9,334 respondents in 1989.  In 1994 and 1998 almost every respondent was correctly sequenced. Only 57 and 46 respondents were incorrectly skipped through part of the survey in each year respectively.  Moreover, most of the respondents were only incorrectly skipped in a single question. In 2004 there were 349 respondents who were incorrectly skipped through one percent of their questions and 22 who were incorrectly skipped through 2 percent or more.

Table 1. Number of Respondents with Missing Data in 1979 Survey

Number of
Questions
Number of Respondents   Percent of
Questions
Number of Respondents
Refused Didn't Know Was Incorrectly
Skipped Over
Refused Didn't Know Was Incorrectly
Skipped Over
0 12527 5084 2347 0% 12620 8185 4313
1 91 2974 1897 1% 43 3247 3421
2 26 1723 1393 2% 7 773 1733
3 13 1016 1158 3% 5 264 989
4 5 629 838 4% 5 101 621
5 2 376 596 5% 0 48 397
6 1 228 489 6% 2 27 312
7 3 173 502 7% 1 18 278
8 3 131 420 8% 1 6 206
9 1 84 340 9% 0 7 118
10 4 57 308 10% 0 2 71
> 10 10 211 2398 > 10% 2 8 227

Table 2. Number of Respondents with Missing Data in 1984 Survey

Number of
Questions
Number of Respondents   Percent of
Questions
Number of Respondents
Refused Didn't Know Was Incorrectly
Skipped Over
Refused Didn't Know Was Incorrectly
Skipped Over
0 11222 4549 7802 0% 11749 7003 8956
1 610 3012 1289 1% 207 3807 1267
2 73 1901 622 2% 44 944 674
3 44 1136 413 3% 13 213 284
4 38 668 252 4% 15 62 133
5 13 345 369 5% 13 21 84
6 6 177 174 6% 10 11 139
7 1 108 93 7% 4 2 137
8 7 63 115 8% 5 3 107
9 4 38 73 9% 2 0 68
10 10 28 64 10% 2 3 36
> 10 41 44 803 > 10% 5 0 184
 
Note: Not included in this table are 617 respondents who did not answer the survey.

Table 3. Number of Respondents with Missing Data in 1989 Survey

Number of
Questions
Number of Respondents   Percent of
Questions
Number of Respondents
Refused Didn't Know Was Incorrectly
Skipped Over
Refused Didn't Know Was Incorrectly
Skipped Over
0 10221 6135 9334 0% 10250 6423 9461
1 171 2517 781 1% 193 3221 843
2 59 1036 189 2% 58 561 51
3 37 395 35 3% 35 219 69
4 20 194 20 4% 13 76 86
5 21 131 16 5% 10 39 24
6 7 75 7 6% 4 24 10
7 10 34 125 7% 4 17 10
8 10 24 18 8% 3 1 5
9 4 10 9 9% 3 3 9
10 7 6 3 10% 3 8 3
> 10 38 48 68 > 10% 29 13 34
 
Note: Not included in this table are 2,081 respondents who did not answer the survey.

Table 4. Number of Respondents with Missing Data in 1994 Survey

Number of
Questions
Number of Respondents   Percent of
Questions
Number of Respondents
Refused Didn't Know Was Incorrectly
Skipped Over
Refused Didn't Know Was Incorrectly
Skipped Over
0 7168 3559 8832 0% 8409 5942 8889
1 1129 1780 57 1% 246 2060 0
2 191 1082 0 2% 81 558 0
3 87 693 0 3% 41 165 0
4 41 443 0 4% 31 79 0
5 28 334 0 5% 20 39 0
6 29 232 0 6% 19 16 0
7 22 171 0 7% 6 15 0
8 21 115 0 8% 10 4 0
9 17 105 0 9% 9 2 0
10 18 72 0 10% 4 2 0
> 10 138 303 0 > 10% 13 7 0
 
Note: Not included in this table are 3,797 respondents who did not answer the survey.

Table 5. Number of Respondents with Missing Data in 1998 Survey

Number of
Questions
Number of Respondents   Percent of
Questions
Number of Respondents
Refused Didn't Know Was Incorrectly
Skipped Over
Refused Didn't Know Was Incorrectly
Skipped Over
0 7248 2497 8353 0% 7850 4741 8385
1 473 1355 21 1% 254 2441 13
2 162 1020 23 2% 86 712 0
3 83 729 0 3% 58 283 1
4 60 589 2 4% 54 110 0
5 42 447 0 5% 27 46 0
6 35 343 0 6% 30 25 0
7 26 277 0 7% 14 11 0
8 19 201 0 8% 4 7 0
9 23 169 0 9% 8 9 0
10 12 120 0 10% 2 5 0
> 10 216 652 0 > 10% 12 9 0
 
Note: Not included in this table are 4,287 respondents who did not answer the survey.

Table 6. Number of Respondents with Missing Data in 2004 Survey

Number of
Questions
Number of Respondents   Percent of
Questions
Number of Respondents
Refused Didn't Know Was Incorrectly
Skipped Over
Refused Didn't Know Was Incorrectly
Skipped Over
0 6531 1524 6539 0% 7006 3185 7290
1 298 993 440 1% 384 2399 349
2 194 755 334 2% 106 1122 18
3 171 624 145 3% 48 477 2
4 78 592 42 4% 40 226 1
5 45 486 98 5% 18 103 0
6 51 387 29 6% 16 68 0
7 45 360 13 7% 10 29 0
8 29 314 3 8% 8 14 0
9 23 235 5 9% 8 17 0
10 11 178 7 10% 3 6 1
> 10 185 1213 6 > 10% 14 15 0
 
Note: Not included in this table are 5,025 respondents who did not answer the survey.