City that subjects were born in is an example of what level of measurement?

A researcher reviews medical records from the past five years to collect data on the relationship between smoking habits and brain cancer. This would be described as a:

An investigator is studying the effect of a new growth hormone injection on height of school aged boys with short stature. He has the boys come into the clinic every 6 months to have their height measured precisely on a calibrated stadiometer. What is the dependent variable?

A researcher plans to study a new medication on patients who have tested positive for HIV, but have not developed AIDS. This medication has shown great results in previous studies. After enrolling subjects, the researcher assigns them to one group, either the control group who receive a placebo or the experimental group who receive the new medication. Since the medication will be very expensive when it becomes available, the researcher decides to assign those with good medical insurance to the group that receives the medication. His reasoning is that if it works, the subjects with good medical insurance will be able to continue to receive it after the study is completed. He assigns those subjects without medical insurance to the control group since they would not benefit from the medication after the study is completed because they wouldn’t be able to afford it. In this study, which ethical principle would you be most concerned about?

The three vertical lines in the following frequency distribution are marking the measures of central tendency. If you were labeling the vertical lines, what is the correct order of the measures of central tendency from smallest value to largest value (from the left to the right)?

A researcher designed a study to examine the effects of calcium supplementation on bone density. She randomly assigned subjects to either receive no calcium supplementation, receive the ADA recommended dose of calcium supplementation, or to receive twice the ADA recommended dose of calcium supplementation. After 6 months, she measures the bone density of all subjects and she wants to compare the mean bone density of the three groups. She also wanted to examine if the effect of calcium supplementation on bone density was different between women under 50 years old and women over 50 years old. What statistical test would be best to study these questions?

Which of the following study design characteristics is found in Experimental studies but NOT in Quasi-experimental studies?

A researcher is studying whether there is a decrease in central line associated blood stream infection (CLABSI) rates among medical ICU patients when hubs are scrubbed with chlorhexidine instead of alcohol. In, this example, what is the dependent variable?

A researcher is studying whether music therapy is effective in decreasing anxiety among adolescent pre-operative patients. Adolescents will be randomized to a group that listens to music before surgery or a group that receives standard care (no music offered). Right before they are taken to the OR, patients are asked to fill out a ANX scale that measures anxiety. In this example, what is the independent variable?

A researcher is studying the effectiveness of a job training program with unemployed homeless women. She provides the job training program to a group of unemployed homeless women and then determines their employment status 3 months, 6 months, 1 year, 3 years, 5 years, and 10 years after the training is complete. The threat to internal validity that she should be most concerned about is: