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A researcher has recruited 20 volunteers to participate in a study. The researcher wishes to measure the effect of alcohol on an individual's reaction time. The 20 volunteers are randomly divided into two groups. Group 1 serves as a control group in which participants drink four 1-ounce cups of a liquid that looks, smells, and tastes like alcohol in 15 -minute increments. Group 2 serves as an experimental group in which participants drink four 1 -ounce cups of 80 -proof alcohol in 15 -minute increments. After drinking the last 1 -ounce cup, the participants sit for 20 minutes. After the 20 -minute resting period, the reaction time to a stimulus is measured. (a) What type of experimental design is this? (b) Use Table I in Appendix A or a random-number generator to divide the 20 volunteers into groups 1 and 2 by assigning the volunteers a number between 1 and \(20 .\) Then randomly select 10 numbers between 1 and \(20 .\) The individuals corresponding to these numbers will go into group \(1 .\)

Step by step solution

01

Title - Determine the Experimental Design

This experiment is designed to compare the reaction times between the control group and the experimental group. Each volunteer is randomly assigned to either group 1 or group 2, making it a Randomized Controlled Trial (RCT). This type of design is used to eliminate bias and ensure that any effects observed are due to the intervention of interest.

02

Title - Assign Numbers to Volunteers

Assign each of the 20 volunteers a unique number between 1 and 20. Volunteers will be identified by these numbers for the purpose of randomization.

03

Title - Randomly Select 10 Volunteers for Group 1

Using Table I in Appendix A or any random-number generator, select 10 unique numbers between 1 and 20. These numbers correspond to the volunteers who will be assigned to Group 1 (the control group).

04

Title - Assign Remaining Volunteers to Group 2

The remaining volunteers, whose numbers were not selected in the previous step, will be assigned to Group 2 (the experimental group). This ensures that both groups have an equal number of participants.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Randomized Controlled Trial

A randomized controlled trial (RCT) is a type of scientific experiment used to measure the effectiveness of an intervention. In this study, the researcher wishes to measure the effect of alcohol on reaction time. RCTs are considered the gold standard in experimental design because they help to eliminate bias. By randomly assigning participants to the control or experimental group, RCTs ensure any observed effects are due to the intervention rather than other variables. Randomization ensures that both known and unknown confounding factors are evenly distributed between the groups.

Control Group

The control group is essential in an RCT as it provides a baseline to compare the effects of the intervention. In the provided study, the control group (Group 1) consumes a liquid that looks, smells, and tastes like alcohol but does not contain alcohol. This helps to isolate the effect of alcohol consumption by showing changes in reaction time that occur without the alcohol. Without a control group, it would be difficult to determine whether any changes in reaction time were directly due to the intervention (alcohol).

Experimental Group

The experimental group in an RCT receives the intervention or treatment being tested. In this study, Group 2 is the experimental group and consumes four 1-ounce cups of 80-proof alcohol. By comparing the reaction times of the experimental group with those of the control group, researchers can determine the effect of alcohol on reaction time more accurately. Any difference in reaction times between the two groups can be attributed to the consumption of alcohol since randomization ensures other variables are balanced.

Randomization

Randomization is a critical process in RCTs that involves randomly assigning participants to either the control group or the experimental group. This is done to prevent selection bias and to distribute confounding variables evenly. In the study, volunteers are assigned numbers and these numbers are then randomly selected to form the groups. Randomization ensures that each participant has an equal chance of being assigned to any group, making the results more reliable and the study more credible.

Reaction Time Measurement

Reaction time measurement is a key aspect of this experiment, as it provides quantifiable data on how quickly participants respond to a stimulus after consuming the liquid. After the participants in both groups have consumed their respective drinks and rested for 20 minutes, their reaction times are measured. This measurement helps in determining the impact of alcohol on reaction speed. Reliable and accurate reaction time measurements are crucial for drawing valid conclusions from the study. Therefore, it is important that the measurement process is consistent for all participants.