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. Design: Single group post-test only
B. Internal Validity Threats.
2. Design (R) 01 X 02
(R) 01 02
B. Internal Validity Threats
3. Design: Pretest-posttest design with experimental and comparison group
B. Internal Validity Threats
4. Design: O X O
B. Internal Validity Threats
5. Design: Single group with three pretests and four posttests.
B. Internal validity Threats
1xa
1. Design: Single group post-test only
For this design, there is only one group and a post-test is conducted after the intervention. The threats to internal validity in this design include:
- History: External events or factors that could influence the outcome between the pre-test and post-test. For example, if there was a major event during the study period that could affect the participants' behavior.
- Maturation: Natural changes in participants over time that could influence the outcome. For example, if participants naturally improve or deteriorate in their abilities without any intervention.
- Testing: Taking the post-test may influence participants' performance if they become familiar with the test or if their motivation changes.
- Instrumentation: Any changes in the measurement instrument or methods of data collection between the pre-test and post-test may affect the results.
2. Design (R) 01 X 02
(R) 01 02
This design involves random assignment of participants to two groups. Group 1 receives an intervention (X) between two measurements (01 and 02), while Group 2 only receives the measurements. The threats to internal validity in this design include:
- Selection: Differences between the groups before the intervention that could influence the outcome. Random assignment minimizes this threat, but there could still be chance differences.
- History: External events or factors that could influence the outcome between the pre-test and post-test.
- Maturation: Natural changes in participants over time that could influence the outcome.
- Testing: Taking the pre-test and becoming familiar with the test may influence participants' performance in the post-test.
- Instrumentation: Any changes in the measurement instrument or methods of data collection between the pre-test and post-test may affect the results.
- Mortality: The loss of participants from one group more than the other, which could bias the results.
3. Design: Pretest-posttest design with experimental and comparison group
In this design, there are two groups - an experimental group that receives the intervention and a comparison group that does not. Both groups are measured before and after the intervention. The threats to internal validity in this design include:
- Selection: Differences between the two groups before the intervention that could influence the outcome. Random assignment helps to minimize this threat, but if participants self-select into groups, there may still be systematic differences.
- History: External events or factors that could influence the outcome between the pre-test and post-test.
- Maturation: Natural changes in participants over time that could influence the outcome.
- Testing: Taking the pre-test and becoming familiar with the test may influence participants' performance in the post-test.
- Instrumentation: Any changes in the measurement instrument or methods of data collection between the pre-test and post-test may affect the results.
4. Design: O X O
This design includes a pre-test, an intervention (X), and a post-test. The threats to internal validity in this design include:
- Selection: Differences between the participants before the intervention that could influence the outcome. Random assignment can help minimize this threat, but if participants are not randomly assigned, there may be systematic differences.
- History: External events or factors that could influence the outcome between the pre-test and post-test.
- Maturation: Natural changes in participants over time that could influence the outcome.
- Testing: Taking the pre-test and becoming familiar with the test may influence participants' performance in the post-test.
- Instrumentation: Any changes in the measurement instrument or methods of data collection between the pre-test and post-test may affect the results.
5. Design: Single group with three pretests and four posttests.
In this design, there is only one group, and multiple pre-tests and post-tests are conducted. The threats to internal validity in this design include:
- History: External events or factors that could influence the outcome between the pre-tests and post-tests.
- Maturation: Natural changes in participants over time that could influence the outcome.
- Testing: Taking multiple pre-tests and post-tests may influence participants' performance and motivation.
- Instrumentation: Any changes in the measurement instrument or methods of data collection between the pre-tests and post-tests may affect the results.