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Sample Size Determination with Two-Sample t Test

16 Questions

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Sample Size Determination with Two-Sample t Test

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Questions and Answers

What is the effect size in the population relevant for the study?

0.5 (correct)

In a power analysis, what does the significance level α of 5% indicate?

The reliability of the effect size estimate

The probability of making a Type I error (correct)

The confidence interval for the sample mean

The degree of variability in blood pressure readings

Why does the sample size need to be doubled if values in the table refer to one group?

To account for two-tailed hypothesis testing (correct)

To ensure adequate representation of both control and treatment groups

To reduce the effect size estimate

To increase the power of the study

What does a power level of 80% signify in a power analysis?

The probability of detecting a true effect Signup and view all the answers

Which factor directly influences the required sample size in a power analysis?

Difference in blood pressure before and after intervention Signup and view all the answers

What is the purpose of using G*Power or similar software in sample size determination?

To calculate statistical power and determine required sample sizes Signup and view all the answers

What is the purpose of conducting a power analysis before a study?

To determine the required sample size to detect a specified effect size Signup and view all the answers

In the context of the given example, what does the effect size of 0.5 represent?

The expected difference in blood pressure between the treatment and control groups Signup and view all the answers

What is the allocation ratio in the given example?

1:1 Signup and view all the answers

What is the total sample size required for the study based on the power analysis?

128 Signup and view all the answers

Which of the following is NOT a required input for the power analysis in the given example?

Standard deviation of the outcome variable Signup and view all the answers

What is the purpose of conducting a power analysis in the given research study?

To determine the minimum sample size required to detect a clinically important difference between the treatment groups Signup and view all the answers

What is the effect size (d) based on the given information?

0.5 Signup and view all the answers

In a randomized controlled trial, what is the purpose of having a control group?

To serve as a baseline for comparison with the treatment group Signup and view all the answers

What is the significance level (α) chosen for the statistical analysis in this study?

0.05 Signup and view all the answers

If the standard deviation of blood pressure in the population changes from 20 mmHg to 15 mmHg, how would the effect size (d) be affected?

The effect size would increase Signup and view all the answers