## Answers

Question 11:- odds ratio for each category is as below

odds ratio = ad/bc

odds ratio= 8×785/68×622

= 0.15

odds ratio = 8×482/ 68×498

=0.11

odds ratio = 8×195/68×402

=0.06.

odds ratio= 8×1462/68×1522

=0.11

Question 12:-

Odds ratio for each category is as follows:-

Number of cigarettes | Odds ratio |
---|---|

1-14 | 0.15 |

15 - 24 | 0.11 |

25+ | 0.06 |

All | 0.11 |

Results:- number of cigarettes smoked directly relates to the occurrence of lung cancer