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Brain Games (Example 2) Researchers are interested in testing whether a video game that is designed to increase brain activity actually works. To test this, they plan to randomly assign subjects to either the treatment group (spend 15 minutes per day playing the game) or a control group (spend 15 minutes per day surfing the Web). At the end of the study, the researchers will administer a test of "brain teasers" to see which group has the greater mental agility. Because they suspect that age might affect the outcome, the researchers will create blocks of ages: \(18-25,26-35,36-45\), and \(46-55\). To randomly assign subjects to treatment or control, they will place four tickets in a box. The tickets are labeled with the age groups. When an age group is selected, everyone in that age group will be assigned to the treatment group. They will select two age groups to go to treatment, and two to go to control. Is this an appropriate use of blocking? If so, explain why. If not, describe a better blocking plan.

Step by step solution

01

Understand the Proposed Blocking Plan

In this experiment, the researchers have divided the participants into four age groups: 18-25, 26-35, 36-45, 46-55. For each age group, all members will be assigned to either the treatment group (video game) or the control group (surfing the Web). This assignment is conducted using a random draw.

02

Evaluate the Appropriateness of Blocking Plan

Firstly, dividing participants into different age groups as blocks is valid since age might affect the outcome of the study, especially if older adults and young adults respond differently to the treatment. However, the problem lies in assigning all members of an age group to either treatment or control. This assignment doesn't allow for comparison within the same age group, making it difficult to isolate the effect of the treatment from the effect of age.

03

Propose a Better Blocking Plan

A better blocking plan could involve still blocking by age group as they've proposed, but within each age group, individuals should be randomly assigned to either the treatment or control group. This way, within each age block, one can directly compare the effect of the treatment on brain activity.

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Key Concepts

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

Blocking

Blocking is a fundamental experimental design technique used to reduce the variability in experimental results caused by confounding variables. In the context of the brain games study, researchers use blocks based on age. By grouping subjects into age blocks, like 18-25 or 26-35, researchers can control for the effect of age on the outcomes. This aids in isolating the effect of the video game on mental agility by ensuring subjects are compared within similar age groups. However, in the initial plan, all individuals in an age group are assigned to the same condition, limiting comparison within the group. A better design would entail randomizing the treatment within each block, allowing clearer comparisons and more reliable results.

Random Assignment

Random assignment involves assigning participants to treatment and control groups using a chance process. This is a crucial step to ensure that each participant has an equal chance of being assigned to any group, minimizing bias. In the brain games study, researchers use a random draw to assign age groups to treatment or control. This creates a more credible and trustworthy experiment by mitigating selection bias and ensuring the groups are similar prior to treatment. With true random assignment, individual characteristics like age should evenly distribute across both groups, allowing the treatment's true effect to be observed.

Treatment Group

The treatment group in an experiment is the group of participants exposed to the intervention being tested. In the brain games study, this group will spend time playing the video game designed to enhance brain activity. Through the planned intervention, the research aims to determine if this video game truly improves mental agility. By comparing their performance on brain teasers to that of the control group, researchers can assess this treatment's effectiveness. It's essential that the treatment group is handled identically to the control group in all aspects except for the exposure to the independent variable—here, the brain game—to ensure accurate results.

Control Group

The control group in an experiment serves as a baseline to compare with the treatment group. These participants do not receive the experimental intervention. In the brain games study, the control group will spend their time surfing the Web instead of playing the game. The control group helps establish whether the brain game's effects differ from the normal activity level represented by web surfing. Importantly, both groups should receive similar conditions aside from the independent treatment, so that any differences in outcomes can confidently be attributed to the treatment itself. This supports making valid inferences about the treatment's effect.