Independent t test

Question 1

What different methods of analysis are there?

Answer 1

• Frequency (looking at categorical data and determining whether group membership is non-random)
• Differences (experimental designs) – if there are two conditions it can be a parametric analysis if it meets the requirements
• Relationships (correlational)

Question 2

What’s an independent variable?

Answer 2

The manipulation used by the researcher

Question 3

What’s a dependent variable?

Answer 3

The outcome measured by the researcher

Question 4

What’s an independent t test and what can it also be called?

Answer 4

Different independent participants in each group.

Also sometimes called:
• Between subjects
• Two-sample
• Unpaired

Question 5

What is a repeated t test and what else is it called?

Answer 5

Same participants repeat the experiment in each condition.

Also sometimes called:
• Within subjects
• Dependent
• Paired sample

Question 6

What could experimental variance be due to?

Answer 6

• Due to experimental manipulation

* Variability between conditions

Question 7

What types of variance are there?

Answer 7

Experimental and random

Question 8

What could random variance be due to?

Answer 8

• Due to measurement error
• Due to individual differences (e.g., BMI)
• Due to unmeasured variables (e.g., participants eating more or less on the day or the temperature)
• Variability within conditions

Question 9

What is the t test equation measuring?

Answer 9

It’s the overall difference in the sample divided by the variability in the sample.

Question 10

What does a large t value mean?

Answer 10

• The larger t value, the greater the ratio of experimental variance to random variance.
• A large t value means the variability is best explained by your experimental manipulation (the independent variable).

Question 11

What’s a null hypothesis?

Answer 11

There will be no difference

Question 12

What is a two tailed hypothesis?

Answer 12

That there will be a difference but the direction is not specified

Question 13

What is a one tailed hypothesis?

Answer 13

There will be a difference between a group and the direction is specified

Question 14

How do you report a t test?

Answer 14

t (df) = calculated value, p < .05

Question 15

How do you present your result?

Answer 15

Use the means to interpret the direction of any significant findings.

Report both mean and SD.

Present descriptives in the text, or in a table or a graph (not all!)

(See page 7 of notes for more help + an example)