1.A comparison showed that mothers who drink large amounts of alcohol during pregnancy give birth to children with a shorter length, lower weight, smaller head circumference and higher frequency of malformations than other children. Identify three potential confounding factors that should be taken into account if one wishes to draw conclusions about the effect of exposure to alcohol on the child's length, weight and head circumference as well as the risk of malformations. [3 points]

2. A cross-sectional study of Down syndrome has found an association with birth order.What could be a cause of confounding and how would you avoid it? [2 points]

3. During a 10-year period, 700 cases of hip dysplasia occurred in a retirement community in Florida.The retirement community had 3,000 residents in the beginning of the study period and 2,200 at the end of the study period. Which measure of disease occurrence can be calculated? Calculate and interpret it. [2 points]

4. List two ways for disease prevalence to increase. [2 points]

1.__________________________

2.__________________________

5. List two ways for disease prevalence to decrease. [2 points]

1.__________________________

2.__________________________