Question

For each of the following cases [(a), (b), and (c)], (I) state whether the study should be observational or experimental. (II) state whether the study should be run blind, doubleblind, or neither. If the study should be run blind or double-blind, who should be blinded?(a) An investigation of whether taking aspirin reduces one’s chance of having a heart attack.(b) An investigation of whether babies born into poor families (family income below $25,000) are more likely to weigh less than 5.5 pounds at birth than babies born into wealthy families (family income above $65,000).(c) An investigation of whether the size of the midsagittal plane of the anterior commisssure (a part of the brain) of a man is related to the sexual orientation of the man.

Answer 1

Answer:

(a) An investigation of whether taking aspirin reduces one’s chance of having a heart attack.

Experimental

Neither blind nor double-blind (unless a placebo is being administered to some participants).

(b) An investigation of whether babies born into poor families (family income below $25,000) are more likely to weigh less than 5.5 pounds at birth than babies born into wealthy families (family income above $65,000).

Observational

There is no blinding issue here.

(c) An investigation of whether the size of the midsagittal plane of the anterior commissure (a part of the brain) of a man is related to the sexual orientation of the man.

Observational

There is no blinding issue here.

Step-by-step explanation:

An observational study happens where some variables are observed to determine their correlations.   On the other hand, in experimental studies, the researcher controls certain variables to determine causality.  Therefore, an experimental study provides evidence of cause and effect, like in (a) above.