SOAN 2120 Lecture Notes - Random Assignment, Selection Bias, Statistical Significance

• School: University of Guelph
• Department: Sociology and Anthropology
• Course: SOAN 2120
• Professor: David Walters

Document Summary

Experimental designs independent variable dependent variable (differences in outcomes between two groups) Equivalent: average scores on the dependent variable and, scores on all other variables which are likely to affect the dependent variable. How do we establish the equivalence of two or more groups: random number tables, objective: equal probability of being assigned to the group. Even with ra the two (or more) groups will not be exactly equal in all respects. If the assignment is random, we can use tests of statistical significance (manipulation vs. random variation) Equivalent proceed as if random assignment had taken place. X represents an experimental variable or effect (the independent variable) Subscripts (scripts) depict the observation; the exact ordering of the numbering is somewhat unimportant. This experiment has a pre-test and post-test. First (the top group) gets the change. The pre-test for the experiment group (o1) The pre-test for the control group (o3) Different levels of the independent variable (different treatments)