1. 1-When would a researcher collect data on all the subjects in the population as opposed to working with only a random sample of subjects? Compare advantages and disadvantages of sampling the subjects.
2. 2-How can research subject samples be chosen so that bias is minimized? Why are voluntary responses and convenience samples considered sources of sampling bias?
3. 3-Suppose your research area is the effect of exposure to cell phone radiation on breast milk production. Give examples of study designs for prospective, retrospective and cross- sectional options.
4. 4-How would you interpret a correlation coefficient of -0.95 between the two parameters; age of the patient and the testosterone level? How would your interpretation change if the coefficient was 0.03 or 0.48?
5. 5-You want to study the relationship between daily alcohol consumption and prostate-specific antigen levels. It was suggested that these two parameters have a linear relationship and as you increase your alcohol consumption your prostate-specific antigen level increases. What kind of a linear model would represent this relationship?
6. 6-A study was conducted to examine the gender difference in daily smoking prevalence. State the research and null hypotheses for this test.

this is the only thing I got. I need answers with full explanation. pls help