Scenario 2: Time Restricted Feeding

Please use the research scenario presented below to answer Questions 6-10.

As part of a pilot study intended to establish effect size estimates for conducting power analyses for future studies, Antoni et al. (2018) spent two weeks tracking the nutrition indicators of a group of 16 study volunteers (92% female) recruited from a town in the UK. At the end of the two weeks, these baseline measures were used to assign participants to a control group (n = 7) or to a time restricted feeding (TRF) schedule (n = 9). The researchers used the baseline measures to assign participants to the conditions so as to ensure that there were "no statistical differences in average age, BMI [body mass index] and body fat between groups" at the start of the study (p. 2). Participants in the time restricted feeding schedule ate breakfast 90 minutes later and dinner 90 minutes earlier than usual during a ten week period. Participants in the control group were asked to maintain their usual eating habits during this same ten week period. Dietary assessments were made at the beginning of the study (baselline) and at the end of the study (week 10) in order to measure energy intake. Body weight, body fat, and fasting biochemistry (glucose, insulin, lipids) were also assessed in week 10. Altogether, 13 of the original 16 participants (6 in the control group and 7 in the treatment group) completed the full 10 weeks of the study.

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Question 68 pts

Antoni et al. (2018) used which method to assign participants to conditions?

Group of answer choices

non-probability sampling

equating

probability sampling

matching

random assignment

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Question 78 pts

Antoni et al. (2018) used which method to recruit and sample participants?

Group of answer choices

non-probability sampling

random assignment

matching

probability sampling

equating

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Question 88 pts

As part of their analyses, Antoni et al. (2018) examined if there was an interaction between the intervention group (time restricted feeding vs. control) and time (baseline vs. 10 week) in relation to the outcome variable "energy intake". The results of the analysis are graphed in the figure below. The P-value represents the intervention group x time interaction. TRF = time restricted feeding.

Based on the information provided, which of the following reflects the best interpretation of the data?

Group of answer choices

There is a significant main effect of time, but no main effect of intervention group. At Time 1, the intervention groups did not differ from one another in their total daily energy intake. But at Time 2, the intervention group consumed had lower daily energy intake than the control group.

There is a significant interaction between intervention group and time. Between Time 1 and Time 2, the TRF intervention caused a decrease in daily energy intake. There were no changes in the baseline control condition between Time 1 and Time 2.

There are no significant main effects or interactions. Neither the intervention group nor time was associated with the daily energy intake.

There is a significant main effect of intervention group, but no main effect of time. Between Time 1 and Time 2, the TRF intervention caused a decrease in daily energy intake. There were no changes in the baseline control condition between Time 1 and Time 2.

There is a significant main effect of intervention group, but no main effect of time. At both Time 1 and Time 2, the intervention group differed from the control group in daily energy intake.

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Question 98 pts

Assume Antoni et al. (2018) want to use a two-step hierarchical regression analysis to examine the association between exposure to the treatment and Week 10 fasting bloodmarkers, while controlling for age, baseline body fat, and baseline BMI. In this analysis, which variable(s) would be the criterion variable? [Select all that apply]

Group of answer choices

Week 10 fasting bloodmarkers

Exposure to the treatment

Baseline BMI

Age

Baseline body fat

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Question 108 pts

Imagine that a peer reviewer were to request additional information about the three participants that dropped out of the study because the reviewer was concerned that the loss of these participants may have impacted the overall results of the study. In this case, the peer reviewer would be expressing concern about a potential ___________ threat to the internal validity of the study.

Group of answer choices

maturation

history

placebo

selection

attrition