Ugrás a tartalomhoz


Renáta Németh, Dávid Simon


Control: introducing one more variable

Control: introducing one more variable

The aim is to further investigate the relationship between two variables by involving a third variable, the so-called control variable

(In Babbie this is under ’ The elaboration paradigm’)


  • As we saw in the first lesson at Simpson’s Paradox, the relationship between ’Company’ and ’Employees Hired by Ethnic Background’ changed if we also looked at ’Level of Education’ as a control variable.

  • Also, the relationship between ’Frequency of seeing a Doctor’ and ’Smoking’ would weaken or disappear if we involved ’Gender’ as a control variable.

The objective of using a control variable may vary according to its position in the causal relationship:

  • explaining an apparent relationship (smoking vs seeing a doctor)

  • finding an intermediary relationship

  • discovering an extra influence

  • (other types)