A nurse was hired by a governmental ecology agency to investigate the impact of a lead smelter on the level of lead in the blood of children living near the smelter. Ten children were chosen at random from those living near the smelter. A comparison group of seven children was randomly selected from those living in an area relatively free from possible lead pollution. Blood samples were taken from the children and lead levels determined. The following are the results (scores are in micrograms of lead per 100 milliliters of blood.
Children living near smelter Children living in unpolluted area
a. What is the null hypothesis?
Living near the smelter does not impact the level of lead in the blood.
b. What is the alternative hypothesis?
Living near the smelter does positivley impact the level of lead in the blood.
g. Estimate the size of the real effect using omega squared and cohen’s d. Is the effect a large one?
g. Do you satisfy the assumption of homogeneity of variance? How do you know?