Lecture 12

Question 1

Lecture 12:

What is a T-Test?

Answer 1

Compares the means of 2 different groups of samples (2 levels of independent variables)

Question 2

Lecture 12:

If a t-test is properly designed, what can it determine?

Answer 2

Can determine causation

Question 3

Lecture 12:

What are 3 examples of Independent Variables in t-tests?

Answer 3

1.) Groups of people
2.) task conditions
3.) time points

Question 4

Lecture 12:

What 5 things need to be valid for an independent t-test?

Answer 4

1.) Data is interval or ratio (check measurement)
2.) Random selection (check research design)
3.) Normal distribution (skew & kurtosis values)
4.) Homogeneity of Variance (variance for 2 groups = similar)
5.) done prior to conduction test & may need to use a non-parametric test if assumptions are not met

Question 5

Lecture 12:

What are the 6 steps to conducting an independent t-test?

Answer 5

1.) states the null & research hypothesis
2.) set the level of risk associated with the null hypothesis (alpha 0.05 if 2-tailed or 0.10 if 1-tailed)
3.) select appropriate test statistic ( & assumptions)
4.) compute the t-obtained test statistic value
5.) calculate the degrees of freedom
6.) determine the t-critical value

Question 6

Lecture 12:

What is a Two-Tailed hypothesis?

Answer 6

When a difference exists between the groups so there is no prediction of whether the difference will be positive or negative

Question 7

Lecture 12:

What is a One-Tailed hypothesis?

Answer 7

Predicts the direction of the difference between the groups

Question 8

Lecture 12:

What is the T-obtained Test Statistic?

Answer 8

Measures the difference between the means
- similar to the Z value but corrected for small group sizes

Question 9

Lecture 12:

Define “Degrees of Freedom”

Answer 9

The number of scores that are free to vary
—> df = n-1

Question 10

Lecture 12:

How do you determine the critical value?

Answer 10

Critical value is determined using a table to find the specific df & alpha levels based on your hypothesis

Question 11

Lecture 12:

What are 5 ways that you can improve your chances of rejecting the null hypothesis?

Answer 11

1.) increase degrees of freedom (larger sample, reduces t-critical)
2.) one-tailed a value (reduces t-critical)
3.) reduce the standard deviation (increase obtained t value)
4.) increase effect size (reduces t-critical)
5.) select a larger alpha value (reduces t-critical)

Question 12

Lecture 12:

What is a repeated measures t-test?

Answer 12

Tests the same subjects twice which reduces standard error & increases degrees of freedom