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PHC 6000: Testing

Introduction to epidemiology: Hypothesis testing

QuestionAnswer
What is Type I error? Rejecting the null when it is true = alpha
What is alpha? Probability of rejecting the null when it is true = Type I error
What is Type II error? Accepting the null when it is not true = beta
What is beta? Probability of accepting the null when it is not true = Type II error
What type of error is convicting an innocent person? Type I error
What type of error is letting a criminal go free? Type II error
What is the approx standard margin of acceptable Type I error? 0.05
What is the approx standard margin of acceptable Type II error? 0.20
What is power? Probability of correctly rejecting the null
What is the approx standard amount of minimum power? 0.80
What is the relationship between alpha and beta? Inverse relationship. Lower alpha = higher beta
What is the effect of a lower alpha on the strength of statistical evidence necessary? with a lower alpha it will take much stronger statistical evidence to ever reject the null hypothesis, even if it is false.
When should one minimize the amount of Type I error? When the cost of rejecting the null is high
If there was a criminal trial or some other very serious life-changing event, would it be better to have a low or high alpha? A lower alpha is better because the cost of rejecting the null is high
Is it always important to minimize Type 1 error? When there is an interest in changing the status quo and the cost of rejecting the null is low, a higher margin of Type I is acceptable.
If there was a non-invasive treatment being tested, would it be better to have a low or high alpha? A higher alpha would be acceptable
What is the null value for risk ratio? 1
What is the null value for risk difference? 0
When should nonparametric tests be used? Should be used on samples that are non-random (e.g., convenience samples)
What is the definition of a 95% confidence interval? If the research were done 100 times in the targeted population, the true effect will lie between the specified range 95% of the time
What information does the p-value provide? Whether or not there is a significant difference
What information does the point estimate and confidence interval provide? Size of difference, precision of the estimate, and likelihood of significant effect if sample size is increased
How can one estimate the likelihood of significant effect if sample size is increased? Look at the confidence interval; a disproportionately large interval on either side of the null tells us that if we increase the sample size, we will likely get a significant result.
What is the difference you want to be able to detect called? Delta/effect size
Which type of study doesn't have an effect size? Descriptive studies
What is observing a difference when in truth there is none called? Type 1 error
What is failing to observe a difference when there is one called? Type 2 error
If two confidence intervals overlap, are they significantly different? No
What is the alpha-level of study? The amount of Type 1 error that's tolerable for a given study
Created by: AlneciaPHS