5. Statistical Significance Testing Flashcards
What is a statistical significance test?
It measures the strength of evidence with which the data sample supplies for or against the null hypothesis
What is the null hypothesis?
It usually relates there being no difference between groups or no effect
How is the null hypothesis measured?
Using the p value, this gives the measure of compatibility between the two groups
What is a p value?
It is a measure of probability of getting the observed data if the null hypothesis were true.
Therefore, if there is a small p value, it determines there is a low probability of getting the data if the null hypothesis were true.
What does a small P value mean?
0.001 - 1 in 1000 that a sample as extreme as that observed would have occured had the null hypothesis been true.
It means that it is unlikely to have occured if the null hypothesis were true.
The observed sample is significantly different from the hypothesised population value.
Disproves the null hypo
What does a high P value mean?
It means that there is a high probability that the data obtained is consistent with the null hypothesis
What is the confidence interval?
A range of population values with which the sample data are compatible.
A range of values in which we are confident that our sample value lies within.
What is a 95% confidence interval?
We are 95% confident that this interval contains our mean.
What is the issue with a large confidence interval?
Large CI suggests a small sample size has been selected. In smaller sample sizes the mean and SD are more likely to be affected by extreme values.
