Data Issues

Waves 1 to 7
Data issues - Waves 1 to 7 – February 2019

11 Smoking inside the household

In Wave 3 there was a higher number of families recorded as having five or more people who smoked inside the household than in other waves (see Tables 22 and 23 below).

Table 22: Number of residents who smoke inside - B cohort
B cohort No. residents smoke inside
Wave 1 % Wave 3 % Wave 4 % Wave 5 % Wave 6 %
Refused (-3) 0 0.0 0 0.0 16 0.4 8 0.2 2 0.1
Not answered (-9) 766 15.0 0 0.0 184 4.3 251 6.1 217 5.8
Missing (.) 40 0.8 1 0.0 0 0.0 0 0.0 0 0.0
0 3,815 74.7 4,060 92.6 3,759 88.6 3,485 85.3 3,276 87.0
1 318 6.2 136 3.1 205 4.8 228 5.6 174 4.6
2 141 2.8 58 1.3 68 1.6 97 2.4 86 2.3
3 18 0.4 3 0.1 6 0.1 13 0.3 6 0.2
4 5 0.1 1 0.0 1 0.0 1 0.0 1 0.0
5 or more 4 0.1 127 2.9 3 0.1 2 0.1 2 0.1
Total 5,107 100.0 4,386 100.0 4,242 100.0 4,085 100.0 3,764 100.0
Table 23: Number of residents who smoke inside - K cohort
K cohort No. residents smoke inside
Wave 1 % Wave 3 % Wave 4 % Wave 5 % Wave 6 %
Refused (-3) 0 0.0 0 0.0 15 0.4 19 0.5 2 0.1
Not applicable (-9) 754 15.3 0 0.0 196 4.7 238 6.0 247 7.0
Missing (.) 54 1.1 1 0.0 0 0.0 0 0.0 4 0.1
0 3,631 73.7 3,939 90.9 3,652 87.6 3,366 85.1 2,994 84.6
1 399 8.1 197 4.5 201 4.8 199 5.0 182 5.1
2 123 2.5 78 1.8 88 2.1 116 2.9 90 2.5
3 15 0.3 3 0.1 10 0.2 12 0.3 9 0.3
4 5 0.1 4 0.1 4 0.1 3 0.1 6 0.2
5 or more 2 0.0 110 2.5 3 0.1 3 0.1 3 0.1
Total 4,983 100.0 4,332 100.0 4,169 100.0 3,956 100.0 3,537 100.0

This difference in response is likely to be due to incorrect recording of 'none' responses as '5' in the instrument, as '5' is the standard way for interviewers to record a 'no' response. In Wave 1 this item was collected as part of the Parent 1 leave-behind form and in Wave 3 this question was collected by the interviewer in a face-to-face interview. However, from Wave 4 onwards this question was changed to a computer-assisted self-interview (CASI), which the respondent completes themselves and, as a result, interviewer reporting error was not an issue. The change in collection mode may have also affected the responses to other categories if there was response bias due to reporting smoking behaviours in a face-to-face interview rather than within the CASI, which is completed alone by the respondent.

To correct this issue, responses to other waves and the number of people in the household were used to either amend the responses or set them to missing where it was unclear what the response should be. Where reported responses to other waves were none, the Wave 3 data were set to none. If other responses were reported in other waves the data was set to missing, with the exception of two cases that reported four or five people smoking in other waves. This resulted in the following changes to the data shown in Tables 24 and 25 below.

Table 24: Wave 3 number of residents who smoke inside amended results - B cohort
B cohort No. residents smoke inside - chb15a4a
Wave 3 (original) % Wave 3 (amended) %
Refused (-3) 0 0.0 0 0.0
Not applicable (-9) 0 0.0 0 0.0
Missing (.) 1 0.0 12 0.3
0 4,060 92.6 4,174 95.2
1 136 3.1 136 3.1
2 58 1.3 58 1.3
3 3 0.1 3 0.1
4 1 0.0 1 0.0
5 or more 127 2.9 2 0.0
Total 4,386 100.0 4,386 100.0
Table 25: Wave 3 number of residents who smoke inside amended results - K cohort
K cohort No. residents smoke inside - ehb15a4a
Wave 3 (original) % Wave 3 (amended) %
Refused (-3) 0 0.0 0 0.0
Not applicable (-9) 0 0.0 0 0.0
Missing (.) 0 0.0 8 0.2
0 3,939 90.9 4,041 93.3
1 197 4.5 197 4.5
2 78 1.8 78 1.8
3 3 0.1 3 0.1
4 4 0.1 4 0.1
5 or more 110 2.5 0 0.0
Total 4,331 100.0 4,331 100.0