REVISION STM3233 LECTURE 4 (HMY)

In a pre-test post-test design where a specific dietary treatment is removed, what is the primary purpose of the post-test?

• To determine the immediate effects of the treatment.

• To assess the sustainability of the treatment's effects after its removal.

• To evaluate the participants' adherence to the treatment.

• To confirm the participants' initial health status.

Answer explanation

The post-test after the removal of the treatment helps to determine whether the benefits of the treatment are sustained or if they dissipate, indicating the treatment's long-term efficacy.

What does the removal of the treatment in a pre-test post-test design allow researchers to observe?

• The placebo effect in the absence of the actual treatment.

• The regression to the mean phenomenon.

• The potential for relapse or rebound effects.

• The effects of a control group's intervention.

Answer explanation

Removing the treatment can reveal whether its effects are temporary or if there's a relapse or rebound in the condition being treated.

In a randomized controlled trial (RCT) examining the efficacy of a new dietary supplement on reducing cholesterol levels, what is the primary purpose of randomization?

• To distribute known and unknown confounding variables equally across treatment groups.

• To eliminate the influence of participant preferences on the study outcome.

• To ensure that the study results can be generalized to the entire population.

• To increase the statistical power of the study.

Answer explanation

Randomization in clinical trials helps to distribute confounding factors evenly across the treatment and control groups, minimizing bias.

What is a double-blind study design in the context of a clinical nutrition trial?

• Both the participants and the researchers are unaware of the treatment allocations.

• Both the researchers and the participants know which treatment is being administered.

• Only the participants are unaware of which treatment they are receiving.

• The data analysts are not aware of which group is receiving the treatment.

Answer explanation

In a double-blind study, neither the participants nor the researchers know who is receiving the active treatment or the placebo, reducing bias.

Why is a placebo often used in a nutrition clinical trial?

• To provide all participants with some form of treatment.

• To increase the sample size of the study.

• To test the efficacy of the treatment against no treatment.

• To make the study more ethical.

Answer explanation

A placebo is used as a control to compare the effects of the active treatment against no treatment, allowing researchers to assess the true efficacy of the treatment.

In a research design that includes more observation in the pretest phase for the control group, what is the primary purpose of these additional observations?

• To identify the natural variation in the outcome of interest without the influence of the treatment.

• To test the effectiveness of the intervention before applying it to the treatment group.

• To assess the placebo effect within the control group.

• To provide extra treatment to the control group.

Answer explanation

Additional pre-test observations in the control group help establish a baseline of natural variation and fluctuations in the outcome, which is essential for comparison purposes when evaluating the effects of the intervention.

Why might a nutrition researcher decide to include more observation points in the pretest phase for a control group in a dietary intervention study?

• To adjust the nutritional intervention based on the control group's data.

• To prolong the duration of the study unnecessarily.

• To have a detailed baseline to which post-intervention changes in the treatment group can be compared.

• To prepare the control group for the treatment phase.

Answer explanation

A detailed baseline allows for a more accurate comparison of changes due to the intervention by understanding the baseline variability.

What is the advantage of having a control group with more observation in the pretest phase in a study examining the impact of a high-protein diet on muscle mass?

• It can demonstrate the diet's effects more clearly by comparing to a well-characterized baseline.

• It ensures that the high-protein diet is the sole variable affecting muscle mass.

• It allows the control group to build muscle mass at the same rate as the treatment group.

• It is used to convince the control group of the benefits of the high-protein diet.

Answer explanation

More observations in the pre-test phase provide a clearer picture of the baseline status, allowing for a more accurate assessment of the diet's effects.