Selecting the most appropriate statistical test

Question 1

Variance

Answer 1

difference in each indiiviaul measuement value and the groups mean

Question 2

standard deviation

Answer 2

the mean, and how close everyone is to it…

Question 3

Normally distributed

Answer 3

symmetrical….. parametric tests… are equal near equal in mena median and mode….

Question 4

Positively Skewed

Answer 4

asymmetrical distribuution one tail longer than another…. median differs from the mean. mean is higher than median, a relatively long upper right tail results, representing a positive skew mean>median

Question 5

Blood pressure… aint normally distributed

Answer 5

NOT INTERVAL!

Question 6

Negatively skewed

Answer 6

a distribution is skewed anytime the median differs from the mean…. mean is LOWER than median…. mean<median

Question 7

skewness

Answer 7

a measure of the asymmetry of distibuution… the perfectly normal distribution is symmetric and has a skewness value of zero…. Needs to be greater than 2 for it really to be skewed…

Question 8

Required assumptions of Interval data(for proper selection of a parmetric test)

Answer 8

Normally- distributed, equal variances…. randomly-derived and independent

Question 9

3 tests that asses for equal variances btw groups

Answer 9

Bartlett’s test/ Levene’s test/ Kolmogorov-Smirnoff test

Question 10

Errors

Answer 10

an error can be made when incorrectly accepting or rejectioning the null hypothessis

Question 11

Type 1

Answer 11

Rejecting the nully hypothesis when we it is actually TRUE! and you should have accepted it…. like a FP

Question 12

Type 2

Answer 12

Not rejecting the null hypothesis when it is actually false, and you should have rejected it!…. thinking there is no difference when there is no difference… FN

Question 13

p value

Answer 13

statistical test compare differences in variables or to evaluate relatnships btw them…..
1. a test statitics value is calculated
2. the test statistic value is compared to the appropriate table of probabilites for that test
3. a probabilitiy value is obtained; based on the probablit of observing , due to chance alone, a test statistic value as extreme or more extreme than actuall obserev if the groups were equal(not different)
…. THe

Question 14

P value is lower than the pre selected a priori value

Answer 14

5% than we say it IS statistically significant… the value of the test statitic could be as lg as it is by chance alone if the groups were similar… we reject null hypothesis if <5%.. the risk of experienceing a type one error is low

Question 15

interpretation of p value

Answer 15

The probability of making a type 1 error if the null hypothesis is rejected…. ***

Question 16

Power

Answer 16

the ability of a study design and its methodology and the selected test sttistc to detect a true difference if one turly exists and therefore the leve of accuracy isn correctly accepting rejectin the null hypothesis

Question 17

sample size

Answer 17

the larger the sample size, the greater the likelihood ability of detecting a difference if one truly exists… increase in power..

Question 18

difference btw groups deemed significant

Answer 18

the smaller the difference btw groups necessary to be considered significant the greateer the number needed… how big of a difference must there before before we care…

Question 19

baseline rate of outcome

Answer 19

(known/estimated)

Question 20

alpha error rates… a type one error is shown as an alpha error

Answer 20

the confidence of the test, or the elvel of signficance of the test…. the size of the test and is 1- the specificity of the test….

Question 21

beta error rates

Answer 21

1-the power or 1- the sensitivity of the test….

Question 22

Point estimate…

Answer 22

sigal best guess as to relationship

Question 23

confidence interval… (most common 95%)

Answer 23

how the datat spreads around the point estimate… .. red like in single point estimate…

Question 24

95% interpretation

Answer 24

We are 95% confident that the real group difference lies between these to interval numbers. *****

Question 25

interpretation of a 95% CI without a p value

Answer 25

if it crosses 1.0 than it is NOT significant

Question 26

if they are not ratios…

Answer 26

if they cross 0 they are not significant

Question 27

Will have a P value of less than .05 if….

Answer 27

It does NOT cross over 1.0.

Question 28

Does statistical significance confer meaningful clincial signficance?

Answer 28

ALWAYS aske this questions when reveiwng findings…