Design A Study Using Dependent Samples Design

Design A Study That Uses Adependent Samplesdesign And A Study That

1. Design a study that uses a dependent samples design and a study that uses an independent samples design. Be sure to make clear your independent and dependent variables. 2. From the study below find the following: a. To identify the IV and DV b. To evaluate whether each study design reflects appropriately a dependent sample design and an independent sample design. c. In your evaluation provide suggestions to correct the design of each study. Study: Dependent: Researchers want to know if diet effects shedding on dogs. The dog owners would compare how much fur their dogs shed before and after their changed diet. Independent: A cat and a dog, of equal size, were selected to compare the speed of the two groups. Each animal ran a distance of 500 feet 5 separate times. The average of the two animals were compared.

Paper For Above instruction

The design of research studies is fundamental to ensuring valid, reliable, and interpretable results. Two common experimental frameworks are dependent (paired) samples design and independent samples design. These are chosen based on the nature of the research question, the variables involved, and the experimental conditions. This paper will first describe the development of a study employing a dependent samples design and another employing an independent samples design. Additionally, an analysis of the provided example studies will be conducted to evaluate their appropriateness and suggest potential improvements.

Designing a Dependent Samples Study

A dependent samples design, also known as a paired or repeated measures design, involves the same participants or subjects across different testing conditions. It is typically used when the researcher aims to observe changes within the same subjects over time or under different conditions. For example, a study examining the effect of a dietary intervention on dog shedding would employ a dependent design. In such a study, the independent variable is the "diet change," and the dependent variable is the "amount of fur shed" by dogs.

To implement this, researchers would measure each dog's fur shedding levels before the dietary change, then implement the improved diet over a specified period, and measure fur shedding again after the diet change. This within-subject comparison minimizes variability caused by individual differences because each dog acts as its control. The primary advantage of this design is increased statistical power, as variability is reduced by comparing each dog to itself.

Designing an Independent Samples Study

Conversely, an independent samples design involves two or more separate groups of participants that are not related or paired. This design is appropriate when the research question compares the effects of treatments or conditions across different groups of subjects. For example, comparing the running speed between a group of cats and a group of dogs of similar size falls under an independent samples framework.

In this scenario, the independent variable could be "species" (cat vs. dog), and the dependent variable is "running speed." Each group would consist of different animals, and their speeds would be measured under identical conditions. Statistical analyses such as independent t-tests are used to compare these groups while assuming independence of observations.

Analysis of the Provided Studies

Study 1: Dog Fur Shedding and Dietary Changes (Dependent Variables)

This study aims to determine whether diet influences fur shedding in dogs. The key variables are the diet (independent variable) and fur shedding amount (dependent variable). The design involves measuring fur shedding before and after diet modification within the same subjects—dog owners tracking their dogs’ shedding levels over time.

This setup exemplifies an appropriate dependent samples design because the same subjects (dogs) are evaluated twice under different conditions, controlling for individual variability. This within-subject comparison increases sensitivity to detect changes caused by dietary intervention.

Study 2: Comparing Running Speeds of Cats and Dogs

This study compares the average running speed of a cat and a dog, each of equal size. The independent variable is species (cat vs. dog), and the dependent variable is their running speed. Data collection involves each animal running a fixed distance multiple times, with the average speed calculated and compared across species.

However, the design poses some issues regarding independence of observations. Since different animals are involved—one cat and one dog—they constitute separate groups, aligning with an independent samples design. Still, a notable concern is the small sample size (only one cat and one dog), which reduces generalizability and statistical validity. To enhance the study, multiple animals of each species should be tested, and the animals should be randomly selected to control for individual differences.

Suggestions for Improving the Study Designs

For the Dog Shedding Study

Although the current design correctly applies a dependent samples framework, it can be improved by including a control period where dogs’ fur shedding is monitored without dietary changes to account for natural fluctuations. Furthermore, blinding the owners to the purpose of the study may reduce bias in reporting shedding levels. Utilizing objective measures, such as weighing shed fur collected in a standardized manner, can also enhance data accuracy.

For the Animal Speed Comparison Study

The major limitation stems from the small sample size and the use of only one animal per species. To improve, the study should involve multiple cats and dogs with similar characteristics (e.g., age, health status, size). Randomly assigning animals to conditions and ensuring blinding of the observers recording speed can mitigate biases. Additionally, increasing the number of trials per animal and analyzing the aggregated data can provide more reliable, generalizable results.

Conclusion

In summary, choosing the appropriate study design is essential for valid research outcomes. The dog fur shedding study is best suited to a dependent samples design because it involves repeated measures on the same subjects. The animal speed study should employ an independent samples design with multiple animals per group to account for variability and improve external validity. By refining these designs with appropriate controls, larger sample sizes, and objective measures, researchers can enhance the reliability and applicability of their findings.

References

• Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed.). Erlbaum.
• Field, A. (2013). Discovering statistics using IBM SPSS statistics (4th ed.). Sage Publications.
• Gravetter, F. J., & Wallnau, L. B. (2016). Statistics for the behavioral sciences (10th ed.). Cengage Learning.
• Lind, D. A., & Marchal, W. G. (2017). Basic statistics for business and economics. McGraw-Hill Education.
• Pallant, J. (2016). SPSS survival manual (6th ed.). McGraw-Hill Education.
• Tabachnick, B. G., & Fidell, L. S. (2013). Using multivariate statistics (6th ed.). Pearson.
• Wilson, D. M., & Gerstein, L. H. (2020). Experimental research methods in psychology. Routledge.
• Shadish, W. R., Cook, T. D., & Campbell, D. T. (2002). Experimental and quasi-experimental designs for generalized causal inference. Houghton Mifflin.
• Field, A. (2013). Discovering statistics using IBM SPSS statistics. Sage Publications.
• Neuman, W. L. (2014). Social research methods: Qualitative and quantitative approaches. Pearson Education.