Lecture 12 - T-tests

Question 1

What is the research process in psychology?

Answer 1

1. ask a research question
2. review the existing research
3. develop a hypothesis
4. collect data to test your hypothesis

Question 2

Categorical design?

Answer 2

when your looking at the frequency of occurrence across 2 categories

Question 3

Experimental design?

Answer 3

when your manipulating variables to look at differences between groups of participants or conditions

Question 4

Correlational design?

Answer 4

when your looking at relationships between 2 continuous variables

Question 5

What are the 2 types of variables?

Answer 5

• IV = what you manipulate
• DV = what you measure
• the IV is always nominal in experimental design and the DV is always continuous
• in an experimental design your IV can be:
  -> independent (or between subject) measure = different participants are recruited into each of the conditions
  -> repeated (within subjects) measures/ design = 1 group of participants that repeatedly take part in the study under different conditions

Question 6

What do t-tests look at at?

Answer 6

the difference between the 2 experimental conditions and the variability within the experiential conditions

Question 7

What is a parametric test?

Answer 7

• a test that requires data from 1 of the large catalogue of distributions that statistics have described, this is often the assumption that the population data are normally distributed
• a t-test is a parametric test

Question 8

What are the assumptions for a t-test (parametric test)?

Answer 8

• All observations should be independent so that each individuals participants data do not influence any other participants data
• Data should be collected at an interval or ratio level
• Data are (roughly) normally distributed
• Amount of variability should be the same for each condition = homogeneity of variance

Question 9

What is the repeated measures test?

Answer 9

• A test we use when we want to compare 2 sets of data coming from the same group of participants
• We are looking at the difference between the 2 experimental conditions

Question 10

What is the 1 sample t-test?

Answer 10

• use when we only have 1 set of data which we want to compare to a reference value
• the homogeneity of variance is not relevant for 1 sample t-test