You are given results on a case control study on alcoholism and breast cancer, 200m participants with Breast cancer and 200 participants without cancer were selected and questioned on previous alcohol use.
Breast Cancer (+) |
Breast Cancer (-) |
Total |
|
Heavy alcohol use |
40 |
20 |
60 |
No/low alcohol use |
160 |
180 |
340 |
total |
200 |
200 |
400 |
Yule’s coefficient of Association ‘Q’ is given by
0.384615385=Q1(say) (using table 1)
As Q is >0 implies there is a positive association between 'Breast cancer' and "use of alcohol'
Table 1
Breast Cancer (+) denoted 'A' | Breast Cancer (-) denoted 'a' | Total | |
Heavy alcohol use denoted 'B' | 40 (AB) | 20 (aB) | 60 (B) |
No/low alcohol use denoted 'b' | 160 (Ab) | 180 (ab) | 340 (b) |
total | 200 (A) | 200 (a) | 400 (N) |
As it is reported that 15 of the controls [Breast CANCER (-)] did not remember their previous heavy alcohol use and incorrectly reported that they were low alcohol users. So corrected frequency table is shown in Table 2:
0.081967213 =Q2 (corrected) (using table 2)
Table 2 |
Breast Cancer (+) denoted 'A' | Breast Cancer (-) denoted 'a' | Total | |
Heavy alcohol use denoted 'B' | 40 (AB) | 35 (aB) | 60 (B) |
No/low alcohol use denoted 'b' | 160 (Ab) | 180 (ab) | 340 (b) |
total | 200 (A) | 165 (a) | 400 (N) |
Obviously there exists a Bias in this study as Q1 and Q2 are not same and this types of bias is called misclassification bias. Misclassification bias is a types of bias that appear due to negligence of data collection.
You are given results on a case control study on alcoholism and breast cancer, 200m participants...
You are given results on a case control study on alcoholism and breast cancer, 200m participants with Breast cancer and 200 participants without cancer were selected and questioned on previous alcohol use. Breast Cancer (+) Breast Cancer (-) Total Heavy alcohol use 40 20 60 No/low alcohol use 160 180 340 total 200 200 400 Calculate and interpret the appropriate measure of association for this study? You later learn that 15 of the controls [Breast CANCER (-)] did not remember...
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