In: Statistics and Probability
Cantor et al. (1988) reported a study of the relationship between the regular use of hair dye and the development of leukemia. The study entailed 577 leukemia patients and 1245 persons free from the disease (controls) who were questioned concerning their use of hair dye. Forty-three patients and 55 controls claimed to have had significant exposure to hair dye.
a. Carry out the chi-square test of significance to test hair dye use (rate) differences between cases and control.
b. Is there evidence of an association between the use of hair dye and the development of leukemia? If so, is the association true beyond chance?
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Use of hair dye | Developed leukema | Don’t developed leukemia | Total |
Yes | 43 | 55 | 98 |
No | 534 | 1190 | 1724 |
Total | 577 | 1245 | 1822 |
Below is the contingency table :
Row_1 | Col._1 | fo (Observed freq.) | Expected Freq. (fe) | (fo - fe) | (fo - fe)^2 | (fo - fe)^2/fe |
1 | 1 | 43 | 31.03512623 | 11.9649 | 143.1582 | 4.612779827 |
1 | 2 | 55 | 66.96487377 | -11.965 | 143.1582 | 2.13781041 |
2 | 1 | 534 | 545.9648738 | -11.965 | 143.1582 | 0.262211382 |
2 | 2 | 1190 | 1178.035126 | 11.9649 | 143.1582 | 0.121522866 |
Sum | 7.134324484 |