Based on what you know about partial correlation and its uses, think about variables in the following correlational studies that would be prime candidates for control via partial correlation

Based on what you know about partial correlation and its uses, think about variables in the following correlational studies that would be prime candidates for control via partial correlation.

a. A researcher investigated the charge that there were sex-related salary inequities at the district offices of large urban school districts. As a first step, the researcher calculated the correlation between sex (male, female) and annual salary. What would be an appropriate variable to control via partialing?

b. A researcher investigated the relationship between vocabulary knowledge and head circumference in a population of elementary school children. What would be an appropriate variable to control via partialing?

c. A researcher investigated the suspected relationship between IQ and size of family and found lower IQs among later-born individuals (as the number of brothers and sisters increase, the IQ becomes lower). What would be an appropriate variable to control via partialing?

d. A researcher investigated the relationship between learning disabilities and the consumption of junk food (the more junk food consumed by a child, the greater the learning disability). What would be an appropriate variable to control via partialing?