Hypothesis Testing Of Proportions Flashcards
Why use hypothesis tests?
To test and evaluate the significance of treatments and initiatives to see if they are of a significant benefit compared to a previous treatment or no treatment
What is a Chi-squared test used for?
To compare proportions between two independent groups.
Commonly used in randomised controlled trials
Three measures of association are often calculated during analyses of 2x2 table, what are they?
Odds ratio
Relative risk
Absolute risk reduction
What is absolute risk reduction?
The difference in risk between the two treatment groups
E.G Risk in placebo - Risk in treatment
What is the relative risk (RR) or risk ratio?
Is the risk in the treatment divided by the risk in the placebo group
Risk in treatment / Risk in placebo
What is the odds ratio (OR)?
The odds in the treatment group divided by the odds in the placebo group
What are assumptions that can be made from the odds ratio value (<1, >1)?
An OR above 1 indicates that the risk is increased in the treatment group compared to placebo
An OR below 1 indicates the risk is decreased in the treatment group
What are Chi-squared tests for r x c table used for?
To compare an outcome categorical variable with r categories between c independent groups
What is the assumption made when using Chi-squared test for r x c table?
The test is considered reliable if most expected values are greater than 5 and all exceed 2.
If not rows and columns are combined
What is a Chi-squared test for trend used for?
To test whether a proportion increases or decreases as the categories of a group variable increase or decrease
What is the main advantage of using the Chi-squared test for trend?
If there is a trend across categories the test is more powerful than the normal Chi-squared test
More like to detect a significant association
