SOAN 2120 Chapter Notes - Chapter 7: Random Assignment, Internal Validity

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

Document Summary

Random assignment: dividing subjects into groups at the beginning of experimental research using a random process, so the experimenter can treat the groups as equivalent. A method for assigning cases (individuals, organizaions, etc. ) to groups for the purpose of making comparisons. Increases conidence that the groups do not difer in a systemaic way. Random in a staisical or mathemaical sense, not in an everyday sense. Random describes a process in which each case has a known chance of being selected. Unbiased because the probability of selecing a case can be mathemaically determined. Has a pre-test a treatment and a post-test. Has an experimental group, and a control group. Lacks random assignment and are compromises or shortcuts. Used in situaions where it is diicult to use the classical design. Have weaknesses that make inferring a causal relaionship more diicult. One-shot case study design (also called the one-group post-test-only design) Has a treatment and a postest (lacks a pretest)