PASS Statistical Concepts Flashcards
Population meaning in stats
All possible observations of an experiment/study variable
Sample meaning in stats
A selection of observation taken from the population - a small group of the population
Types of errors
Random error due to chance
Systematic error due to bias
What is random error due to?
Due to chance + sampling variation
How to reduce random error
Increasing sample size reduces random error
What is bias quantified by?
The difference between the true value and the expected value
Relationship between random error and sample size
As sample size increases, random error decreases
Relationship between systematic error and sample size
Changing sample size has no effect no systemic error - does not reduce
What is a hypothesis?
A statement that an underlying truth of scientific interest takes a particular quantitative value
What is a p-value?
The probability of getting an observation as extreme as or more extreme than the one observed in the hypothesis is true
When do you reject the null hypothesis at the 5% level?
When p-value < 0.05
What do you do with the null hypothesis at the 5% level when the p-value < 0.05?
Reject null hypothesis
Limitation of hypothesis testing
Rejecting a hypothesis is not always useful:
-statistically significant ≠ clinically important
- statistical significance depends on sample size
What is a 95% confidence interval?
The range within which we can be 95% certain that the true value of the underlying truth really lies
Relationship between confidence interval andsample size increases
As sample size increases, random variation + uncertainty decreases
