| Types of Illness | Wet Areas Population Illness % |
Dry Areas Population Illness % |
O/E Ratio | ||
| Birth defects | 120 births | 24 (20%) | 176 births | 12 (12%) | (2.9%) |
| Nervous breakdowns | 149 adults | 13 (7.0%) | 510 adults | 7 (1.4%) | (6.2%) |
| Urinary disease | 314 total | 22 (7.0%) | 826 total | 21 (2.5%) | (2.0%) |
| Asthma | 314 total | 14 (4.5%) | 826 total | 11 (1.3%) | (3.5%) |
| Hyperactivity | 127 children | 11 (8.7%) | 316 children | 2 (0.6%) | (14.5%) |
Have a good look at the table above. How do you interpret these data? What features of the data and of the way they are assembled affect your interpretation? Consider:
As far as subject selection is concerned, we have no information on nonresponders, and we could have a volunteer effect.
Validity of responses must be judged in the light that the data is based on recall and may well be subject to observer biases. A medical review is necessary.
Competing risk factors: we have no information on confounding.
We have no objective data for exposure to Canal chemicals, so that is unclear and we cannot make a proper assessment.
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