Dr. Stevens wants to examine the relationship between body mass index (BMI) and depression. He selects as his research subjects a sample of American athletes who are currently training for the summer Olympic Games. Dr. Stevens finds no relationship between BMI and depression. Which of the following is one problem with his research design that could have kept him from finding a relationship between those variables?

Restriction of Range.

Explanation: In most research studies such as statistical analysis to delineate the correlation or relationship between variables, choosing subjects to be used in the experiment remains of paramount importance. Once the chosen sample to be used in the experiment isn't representative, then we already have a failed experiment.

Dr. Steven's research sample choice exhibits a RESTRICTION OF RANGE PROBLEM whereby sample does not cut across the entire range or category of variables required to establish a meaningful relationship, hence the sampling population has been shortened or condensed.

the secretary of state, appointed by the president with the advice and consent of the senate, is the president's chief foreign affairs adviser. the secretary carries out the president's foreign policies through the state department and the foreign service of the united states.

for many centuries there were important factors which the economies of the muslim empires developed increasingly. they applied economic procedures in production, investment, finance, taxation and property. they used to tax certain goods (for example: harvest), they charged interest on money lent, they signed contracts with merchants; they relied on a common currency, and they used checks as well as promissory notes. with the money collected by means of taxation, the government provided the needy with an income. in addition, trading networks covered huge distances, so far regions started to have contact and exchange goods. this trade network covered areas of asia, africa and europe.