Independent and dependent variables

• Independent Variable  (I.V.):  The experimental factor you manipulate; the treatment itself.
• Dependent Variable  (D.V.):  The behavior measured; the factor that might be affected by changes in the independent variable.
• Experimental Condition/Group:  The condition that exposes subjects to one version of the independent variable.
• Control Condition/Group:  A condition identical to the experimental one, except the independent variable has a different value, such as zero.
• Random Assignment:  Assigning subjects to conditions by chance, thus minimizing preexisting differences between those in the different conditions.

For each of the following hypotheses, identify the independent and dependent variables.

1. Those who favor the Democratic Party are more likely than those who favor the Republican Party to support restrictions on handguns.
2. The Democratic Party makes a greater effort to involve different constituencies in policy-making than the Republican Party.
3. The amount of officially recorded crime in a neighborhood increases as the frequency of police surveillance of the neighborhood increases.
4. The frequency of innovation in a group is positively influenced by the diversity of experiences of group members.
5. An increase in the average level of education in a country’s population will bring about a decline in fertility rates.
6. The rate of strike activity in an industry will decline as the threat of global competition to that industry increases.
7. As university tuition rates increase, the proportion of students who work at paid jobs will increase.
8. Different-sex friendships tend to be less enduring than same sex friendships.
9. As the unemployment rate in a region increases, per-capita expenditures on leisure and recreation decline.
10. The incidence of gang-related juvenile crime will increase as a city’s teenage unemployment rate increases.
11. The more similar the educational level of spouses, the more likely they are to reach consensus on the division of labor in the household.
12. The more diverse the race and ethnic composition of a school’s student body, the greater the number of inter-racial friendships among students.
13. The greater the isolation of a family from friends and other family members, the greater the likelihood of family violence.
14. The rate of voter turnout in elections will decline as the amount of political corruption in a district increases.
15. There is more continuity in doctor-patient relationships in private than in public hospitals.

Unionization of police departments has no effect on the ratio of promotions based on seniority to promotions based on merit.