t-tests (single sample)

Question 1

How to know if your using a t test vs z test?

Answer 1

The population standard deviation will be unknown.

Question 2

When do you use a single sample t test?

Answer 2

If you need to compare a sample mean to a pop mean. Need to estimate pop standard deviation from sample. There will only be one set of data

Question 3

What is the sample mean?

Answer 3

It is the same as the known population mean (μ)

Question 4

What is the first part in step 2 (determining characteristics of CD)?

Answer 4

Create a table with raw scores, deviation scores and squared deviation scores

Question 5

Whats the first step in calculating the standard deviation?

Answer 5

Estimated population variance:
S* = ∑(X-M)*/ N-1
(sum of squared deviation scores divided by degrees of freedom)

Question 6

Whats the first step in calculating the standard deviation?

Answer 6

Estimated standard deviation:
S = square root of population variance

Question 7

What is the first step in calculating the estimated standard error (standard deviation of DOSM)?

Answer 7

Sm* = S* / N
(estimated pop standard deviation divided by number of scores)

Question 8

What is the second step in calculating the estimated standard error (standard deviation of DOM)?

Answer 8

Sm = square root of variance DOSM

Question 9

How do you calculate the t score in step 4?

Answer 9

t = (M - μ ) / Sm
(sample mean take pop mean divided by standard error)

Question 10

How do you calculate the confidence intervals in step 6?

Answer 10

CI = M+/- (t critical)(Sm)
(sample mean (plus or minus) t critical value times standard error
Upper limit: t critical x Sm + M
Lower limit: t critical x Sm - M

Question 11

What are the confidence intervals that are used in step 6?

Answer 11

CI show a range of values where we assume the true population mean lies. They are used to test a hypothesis of mean difference when estimating a population mean. E.g. if your study used a 95% confidence interval = you are 95% confident the true pop mean is somewhere between the obtained upper and lower limits