Posted: December 18th, 2016

Design: Pretest-posttest design with experimental and comparison group b. Internal validity threats

Please respond to the following questions either by writing the design name or by describing the design using standard notation (X = program, O=observation, R= random assignment). For each design, please discuss all threats to internal validity. 1. a. Design: Single group post-test only b. Internal validity threats: 2. a. Design: (R) O1 X O2 (R) O1 O2 b. Internal validity threats: 3. a.Design: Pretest-posttest design with experimental and comparison group  b. Internal validity threats: 4. a. Design: O X O b. Internal validity threats: 5. a. Design: Single group with three pretests and four posttests b. Internal validity threats