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
1. Design: Single group post-test only
Threats to internal validity:
- History: The results could be influenced by external events or factors that occur between the pre-test and post-test.
- Maturation: There is a possibility that participants could naturally change or develop over time, leading to differences in the post-test scores.
- Testing: Prior exposure to the pre-test could affect participants' performance on the post-test.
- Regression to the Mean: Extreme scores obtained in the pre-test are likely to move closer to the group mean in the post-test, simply due to chance.
- Selection bias: The lack of a comparison group makes it difficult to determine if any changes observed in the post-test are solely due to the intervention, or if other factors may be influencing the results.
2. Design (R) 01 X 02
(R) 01 02
Threats to internal validity:
- History: Similar to the single group post-test only design, external events or factors occurring between the pre-test and post-test could influence the results.
- Maturation: As with the previous design, participants can naturally change over time, leading to differences in the post-test scores.
- Testing: Prior exposure to the pre-test could affect participants' performance on the post-test.
- Instrumentation: Any changes in the measurement instruments or assessors between the pre-test and post-test could introduce bias.
- Selection bias: While random assignment helps control for selection bias, there may still be factors that could influence the outcomes.
3. Design: Pretest-posttest design with experimental and comparison group
Threats to internal validity:
- History: External events or factors occurring between the pre-test and post-test could differently impact the experimental and comparison groups.
- Maturation: Both groups may experience natural changes over time, but these changes could be different between the groups.
- Selection bias: Differences in the characteristics of participants assigned to the experimental and comparison groups may influence the results.
- Instrumentation: Changes in the measurement instruments or assessors between the pre-test and post-test could introduce bias.
- Mortality: Participants dropping out or being lost to follow-up could impact the results if their characteristics differ significantly from those who remain in the study.
4. Design: O X O
Threats to internal validity:
- History: External events or factors occurring between the pre-test and post-test could influence the results.
- Maturation: Participants may naturally change or develop over time, leading to differences in the post-test scores.
- Testing: Prior exposure to the pre-test could affect participants' performance on the post-test.
- Instrumentation: Changes in the measurement instruments or assessors between the pre-test and post-test could introduce bias.
- Regression to the Mean: Similarly to the first design, extreme scores obtained in the pre-test are likely to move closer to the group mean in the post-test, simply due to chance.
5. Design: Single group with three pretests and four posttests.
Threats to internal validity:
- History: External events or factors occurring between the pretests and posttests could influence the results.
- Maturation: Participants may undergo natural changes or development over the course of the study, leading to differences in the post-test scores.
- Testing: Prior exposure to the pretests could affect participants' performance on the posttests.
- Instrumentation: Changes in the measurement instruments or assessors between the assessment points could introduce bias.
- Regression to the Mean: Extreme scores obtained in the pretests are likely to move closer to the group mean in the posttests, simply due to chance.
1. Design: Single group post-test only
For this design, the main internal validity threat is the lack of a comparison group. Without a control group, it is difficult to determine whether any observed changes are truly a result of the intervention or other factors. Other potential threats to internal validity include history (external events that occur during the study period), maturation (participants naturally changing over time), and testing effects (participants becoming more familiar with the assessment instrument).
2. Design (R) 01 X 02
(R) 01 02
This design is a randomized pretest-posttest design. The main internal validity threat for this design is selection bias. Random assignment helps mitigate this threat, but it is still possible that the groups may differ on other variables that affect the outcome. Other internal validity threats include history, maturation, and testing effects.
3. Design: Pretest-posttest design with experimental and comparison group
This design includes an experimental group and a comparison group. The main internal validity threats for this design include selection bias (whether the groups are truly equivalent at the start of the study), history, maturation, testing effects, and instrumentation (changes in measurement over time). There may also be interactions between the experimental treatment and other factors that could affect the outcome.
4. Design: O X O
This design is a simple pretest-posttest design with no comparison group. The main internal validity threats for this design include history, maturation, testing effects, and instrumentation. Without a control group, it is difficult to determine whether any observed changes are a result of the treatment or other factors.
5. Design: Single group with three pretests and four posttests.
For this design, the main internal validity threat is the lack of a comparison group. Without a control group, it is difficult to determine whether any observed changes over time are a result of the intervention or other factors. Other potential threats include history, maturation, testing effects, instrumentation, and attrition (participants dropping out of the study). Additionally, the multiple pretests and posttests could introduce additional threats related to sensitization (participants becoming more aware of the study and potentially changing their behavior) and carryover effects (changes from one test to the next influencing subsequent results).