Topic 6 - t Test

Question 1

When is a single sample t-test used?

Answer 1

Used to test null hypothesis for a single sample experiment when the standard deviation of the population must be estimated

Question 2

What is the formula for t-obs

Answer 2

sample mean - population mean / estimated standard deviation for the sample

Question 3

What is the effect of small samples on accuracy, in terms of standard normal curve?

Answer 3

In small samples, when estimating standard error of the mean with standard deviation of the sample, the standard normal curve does not provide sufficiently accurate probabilities

Question 4

What does the accuracy of estimated sample standard deviation depend on?

Answer 4

Sample size

Question 5

Different t distribution depends on what?

Answer 5

Degrees of freedom

Question 6

Define degrees of freedom

Answer 6

How many scores in sample are free to vary

-Generally all except the last score

Question 7

TRUE OR FALSE

For each df there’s a different t-distribution

Answer 7

TRUE

Question 8

What are the three assumptions of the single sample t- test?

Answer 8

1. The random sample comprises interval or ratio scores
2. Distribution of individual scores is normal
3. Standard error of mean estimated using standard deviation from the sample

Question 9

What are the steps of a simple sample t-test?

Answer 9

1. Calculate the observed t using the estimated standard error of the mean
2. Determine the degrees of freedom (n-1)
3. Look up critical t in the t-table with appropriate df and alpha
4. If observed t is greater than or equal to the tabled value then we reject the null