Exam One - ttests

Question 1

What do ttests do?

Answer 1

estimate the probability that the mean diff between two sets of values can be attributed to chance alone

Question 2

What are the two types of ttests?

Answer 2

independent and paired

Question 3

independent t tests are between two ________- samples

Answer 3

different/unrelated

Question 4

paired t tests are between two ____- samples

Answer 4

similar/related (pre/post)

Question 5

if p<a, we ___ that u1 = u2 and conclude that the two samples are significantly different

Answer 5

reject

Question 6

When do we use ttests? to compare…

Answer 6

• one nominal or ordinal variable
  AND
• one continuous (measurement) variable

Question 7

1 ttest compares ____ dependent variable. if the study has 10 DVs, the _____ ttests are ran

Answer 7

1, 10

Question 8

What kind of ttest is this example?

standing balance (s) in people with and without peripheral neuropathy?

Answer 8

independent ttest

Question 9

What kind of ttest is this example?

standing balance (s) and functional reach (cm) in people with and without peripheral neuropathy

Answer 9

2 independent ttests

Question 10

What kind of ttest is this example?

knee abduction excursion (degrees) during a drop landing with and without an ankle brace

Answer 10

paired ttest

Question 11

What kind of ttest is this example?

thigh and calf circumference (cm) and among adolescents before and after a strengthening intervention

Answer 11

2 paired ttests

Question 12

What are 2 assumptions data must have for ttest to be valid?

Answer 12

1 - equal variance within samples
2 - normally distributed

Question 13

equal variance within groups is represented by the ______ for each group

Answer 13

SD

Question 14

if the data is normally distributed it should not be __________

Answer 14

skewed left or right

Question 15

ttests may be _____if the data has unequal variance or non-normal distribution

Answer 15

misleading

Question 16

Why don’t we do tons of ttests for the study?

Answer 16

it increases the likelihood of type one error study-wide

Question 17

if you reduce the alpha (to account for a ton of ttests) this will ______ the study power

Answer 17

decrease

Question 18

bonferroni correction

Answer 18

• common but conservative method to prevent increase type one error when doing multiple ttests
• take the alpha and divide it by # of comparisons and then thats the alpha level for each comparison

Question 19

Turkey and sheffe adjustments

Answer 19

adjust alpha to account for multiple comparisons (ttests) but are less conservative than bonferroni
- as such they are both more powerful than bonferroni

Question 20

LSD (least significant difference)

Answer 20

• very powerful, doesn’t adjust alpha, basically says fuck it
• for the statistically liberal