Hypothesis Testing & P-Values

Question 1

what is the population

Answer 1

all individuals in which we are interested in

Question 2

what is the sample

Answer 2

Group of individuals drawn from our population of interest, which we study in order to learn about the population

Question 3

main aim of statistical analysis

Answer 3

is to use the information gained from a sample of individuals to make inferences about the population of interest.

There are two basic approaches to statistical analysis:
Estimation (Confidence intervals) 
Hypothesis testing (P-values) .

Question 4

what is the null hypothesis

Answer 4

where No difference (or change) will be observed between the measures and outcome

Question 5

what are the hypothesis testing steps

Answer 5

set the null and alternative H
Choose a sig level for the test
carry out sig test
obtain test stat
compare test statistic to  a distribution we expect  it to follow if the null hypothesis is true 
obtain p-value
make a decision

Question 6

how do you work out the test stat

Answer 6

Observed value - Hypothesised value
/
Standard Error(of the observed value)

Compare this test statistic to a distribution we expect it to follow if the null hypothesis is true (e.g. Normal distribution) to obtain a P-value.

Question 7

what do you use the p-value for

Answer 7

to make a decision about whether to reject, or not reject, your null hypothesis

if it is less than the sig level than the results are significnt

Question 8

what does p-value mean

Answer 8

Probability of obtaining your results, or more extreme results, if the null hypothesis is true .

Question 9

what is the range for a p-value

Answer 9

0-1

Question 10

what does a small p-value mean

Answer 10

your results are unlikely when the null h is true

Question 11

what does a large p-value mean

Answer 11

your results are likly when the null H is true

Question 12

what is a type 1 error

Answer 12

false positive- rejected the null hypothesis, when it is fact true

chance of saying there is no difference, and you say there is

Question 13

what is type 2 error

Answer 13

false negative- not rejected the null hypothesis, when in fact false

Question 14

what is the Power of the study mean

Answer 14

The probability of rejecting the null hypothesis when it is actually false is called the POWER of the study (Power=1-β). It is the probability of concluding that there is a difference, when a difference truly exists.

Question 15

what does a p-value of 0.001 mean

Answer 15

Your results are unlikely when the null hypothesis is true.
, and the results are stat sig, as the P-value is less than the sig level.

There is sufficent evidence to reject the null H and accept the alternative H.

Question 16

what are some Misinterpretation of P values

Answer 16

A common misinterpretation of the P value is that it is:
the probability of the data having arisen by chance
or
the probability that the observed effect is not a real one.

Question 17

does statistical significant mean Clinical Significance

Answer 17

Statistical significance does not necessarily mean the result is clinically significant/ practically important

Question 18

How is Clinical Significance determined

Answer 18

through looking at the CI

Question 19

what is the meaning if a CI includes 0

Answer 19

If the 95% CI does include zero then the hypothesis test will return a non-significant result.

Question 20

what is the meaning if the CI dosen’t include 0

Answer 20

If the 95% CI does not include zero (or, more generally the value specified in the null hypothesis) then a hypothesis test will return a statistically significant result.