16 Questions
What test is used to determine if all the means are equal to each other?
ANOVA
Which test is appropriate for determining if two sample means are equal to each other?
Two-sample t test
When the independent variable is continuous, which statistical measure is used for significance testing?
t-distribution
What statistical test is used to determine if two categorical variables are associated with each other?
Chi-square test
What is the main advantage of a cohort study?
The exposure comes before the outcome, establishing a temporal relationship.
Which study design provides stronger evidence as you move up the pyramid of study designs?
Cohort
What type of data does an epidemic curve show?
Incident cases over time
In an outbreak investigation, which component includes confirmed vs suspected cases?
Case definitions
What happens if the p-value is LESS THAN the alpha level?
We reject the null hypothesis
What happens if the confidence interval does NOT include the null value?
We reject the null hypothesis
Which type of error happens when the null hypothesis is false but you subsequently fail to reject it?
Type II error
What do measures of association help determine?
The relationship between variables
What type of study design involves collecting data on both exposure and outcome status at the same time?
Cross-sectional
Why is it difficult to establish a temporal relationship in cross-sectional studies?
Data on exposure and outcome are collected at the same time
Which type of study design involves comparing people with a particular condition or disease to people without the particular condition or disease?
Case-control
Why cannot risk be directly calculated in case-control studies?
They cannot estimate risk
Study Notes
Hypothesis Testing
- The ANOVA (Analysis of Variance) test is used to determine if all the means are equal to each other.
- The t-test is used to determine if two sample means are equal to each other.
Regression Analysis
- When the independent variable is continuous, linear regression is used for significance testing.
Categorical Variables
- The chi-squared test is used to determine if two categorical variables are associated with each other.
Study Designs
- The main advantage of a cohort study is that it can establish a temporal relationship between exposure and outcome.
- The pyramid of study designs, with randomized controlled trials at the top, provides stronger evidence as you move up.
Outbreak Investigation
- An epidemic curve shows the frequency of new cases over time.
- The case definition component includes confirmed vs suspected cases.
Statistical Significance
- If the p-value is LESS THAN the alpha level, the null hypothesis is rejected.
- If the confidence interval does NOT include the null value, the null hypothesis is rejected.
Errors
- A type II error occurs when the null hypothesis is false but you subsequently fail to reject it.
Measures of Association
- Measures of association help determine the strength and direction of the relationship between exposure and outcome.
Cross-Sectional Studies
- Cross-sectional studies involve collecting data on both exposure and outcome status at the same time.
- It is difficult to establish a temporal relationship in cross-sectional studies because the exposure and outcome are measured simultaneously.
Case-Control Studies
- Case-control studies involve comparing people with a particular condition or disease to people without the particular condition or disease.
- Risk cannot be directly calculated in case-control studies because the sample is not a random sample of the population.
Learn how to compare p-value to alpha level and determine if the confidence interval includes the null value in hypothesis testing.
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