T-Tests

Question 1

Used to determine if your sample is different from a specified population; most commonly applied when the test statistic would follow a normal distribution

Answer 1

T-test

Question 2

t = X-μ/SE 
df = N-1

Answer 2

One sample t test

X is the average

Question 3

The t-distribution is a ______ of ______, which are mound shaped and symmetrical like the standard ________ distribution. However, the t-distribution changes shape has a function of the *______ _______; the “tails” become thicker as ____ decreases

Answer 3

family of curves
normal
sample size
N

Question 4

The ___________ t-test is used when two separate sets of separate but identically distributed samples are obtained, one from each of the two populations being compared.

Answer 4

independent (or two-sample)

Question 5

True or False
This is an example of an independent t-test; suppose we are evaluating the effect of a medical treatment, and we enroll 100 subjects into our study, then randomly assign 50 subjects to the treatment group and 50 subjects to the control group.

Answer 5

True

Question 6

Because the t-test has fatter tails, it will have greater _________, and requires a greater ________ in order to be significant

Answer 6

probability

difference

Question 7

This t-test can answer the question of how does a sample we take, compare with a known norm; for example; does our sample (dental class average age) compare to the known value of average national dental school age

Answer 7

one-sample t-test

Question 8

______ ______ (or _______) t-tests typically consist of a sample of matched pairs of similar units, or one group of units that has been tested twice (a “repeated measures” t-test); for example; a blood pressure measurement before and after something

Answer 8

paired sample (or dependent)

Question 9

Assumptions/Requirements for the t-test; require the dependent value to be _________ (interval/ratio measurement scales), the samples are derived from ________ distributions, the samples are derived from populations with roughly equal ________, (will have equal STDs) the groups are ______ (samples not measured twice); can nominal or _______

Answer 9

continuous
normal
variances
independent
ordinal

Question 10

Use t-distribution when the sample size is _____

Answer 10

small

Question 11

_______ analysis should ideally be done prior to data collection when estimating the sample size

Answer 11

prospective

Question 12

________ analysis may be done adter the experiment

Answer 12

retrospective