Week 7 - The T-Test Flashcards
The T-Test can be used in any situation when…
1) Our dependent variable is continuous (interval/ratio)
2) Our independent variable is categorical (two indistinct experimental conditions
What is a null hypothesis?
There is no difference between experimental conditions
What is an alternative hypothesis?
There will be no difference between the experimental conditions
When do we use a T-Test?
- We can use a T-Test when we have collected data in two experimental conditions, and we want to understand whether the means of those conditions differ a little or a lot
- If the data from our experimental conditions came from the same population, we expect the means will be roughly equal. A large deviation between groups/conditions due to random error is unlikely
- So under the null hypothesis we expect that the means will be very similar
What is standard devaition?
It is the average distance between the data points and the mean
What are we doing in the T-Test?
1) We look at the mean difference and compare it to the difference we would expect in the population if our null hypothesis is true
2) The null hypothesis predicts no difference between the conditions, so in other words the means are equal. So subtracting them would result in 0
3) So the top of our formula literally translates into the difference between means of your two experimental conditions
4) So basically, subtracting 0 will make no difference
What does the T-Test measure?
Is used to measure whether two means differ. Is there a difference between your experimental conditions - Central tendency
However, the T-Test also takes into consideration how much variability is in the data - Dispersion
What T-Test is used for matched pairs?
Paired-samples T-Test
What T-Test is used for repeated measures
Paired-samples T-Test
What T-Test is used for independent groups?
Independent samples T-Test
What T-Test is used for one sample?
One-sample T-Test
