Comparing Means Pt1

Question 1

What is the difference between a ‘within subjects’ and ‘between subjects’ design?

Answer 1

Within subjects is when one group is allocated to 2 or more conditions and between subjects is when two or more groups are allocated to one condition or task.

Question 2

What are the advantages and disadvantages of within and between subjects design?

Answer 2

Within-subjects designs, where each participant experiences all conditions, offer greater statistical power and control for individual differences but may be susceptible to order effects. Between-subjects designs, with different participants in each condition, minimize order effects but require more participants and resources to achieve similar power.

Question 3

What are the different types of T Test?

Answer 3

Independent - Between subjects design (compares the mean of two different groups).

Dependent - Within sibjects design (compares the means of 1 group on two occassions)

One sample - One sample compared with a known population mean e.g., comparing acidity to a neutral PH of 7.

Question 4

What are the T Test assumptions

Answer 4

T Test is a parametric test of difference. It assumes that data is:

• Independent
• Approximately normally distributed
• Have a similar amount of variance within each group being compared (Levene’s)
• DV needs to be continous, IV needs to be categorical

Question 5

What are degrees of Freedom and how are they calculated?

Answer 5

We need DF for making estimates
Definition: The number of scores that are free to vary when estimating a
population parameter from a sample

df = N - 1 (for a single sample t test)

Question 6

What is the difference between a one or two tailed hypothesis?

Answer 6

One tailed
One population mean is greater
than or less than the other
Example: Drug A will be better than
Drug B (direction)

Two tailed
Two populations are different from
one another
Example: Drug A and B will have
different effects (no direction)