Experiments

Full Answer Section

Experiment 3:

• Type of Design: Repeated-measures design
• Justification: This design was chosen because it aimed to compare the effectiveness of two teaching methods within the same group of participants. By testing the same children before and after each teaching scheme, the researchers controlled for individual differences and reduced the need for a separate control group. This design is efficient but requires careful analysis to avoid order effects (e.g., improvement due to practice rather than specific teaching method).

Sources:

• Experimental Design: [[invalid URL removed]]([invalid URL removed])
• Matched-pairs Experiment: [[invalid URL removed]]([invalid URL removed])
• Independent-samples t-test: [[invalid URL removed]]([invalid URL removed])
• Repeated-measures Design: [[invalid URL removed]]([invalid URL removed])

Please note: These are just potential explanations and justifications, and the specific reasoning behind the researcher's choice of design might depend on additional factors not mentioned in the brief descriptions. Always consult the original research paper for a more complete understanding of the study design and rationale.

Sample Solution

Experiment Designs and Justifications:

Experiment 1:

• Type of Design: Matched-pairs experiment
• Justification: This design was chosen because it aimed to control for individual differences in depression severity, a potential confounding variable. By pairing participants based on their initial depression scores, the researchers ensured that any observed differences in treatment effectiveness were less likely due to pre-existing differences in symptoms. This design strengthens the internal validity of the study, allowing for a more accurate comparison of the two therapies.

Experiment 2:

• Type of Design: Independent-samples t-test
• Justification: This design was chosen because it aimed to compare two independent groups (7- and 9-year-olds) without the need for pairing. The researcher likely expected that the age difference itself would be the main factor influencing reading comprehension, making pairing unnecessary. This design is simpler to conduct but may be less robust than a matched-pairs design if individual differences are substantial within each age group.