T - Tests II

Question 1

What is a t - test used for?

Answer 1

Used to determine whether the mean for a sample differs significantly from:

• Mean of another sample drawn from the same population.
• Estimated population mean. (hypothesised mean).

Question 2

What is the purpose of a spirometry?

Answer 2

A measure of flow through the airways.

Question 3

What is COPD?

Answer 3

Constriction of the airways due to smoking.

Question 4

What is a hypothesis?

Answer 4

It is a statement and IS NOT the same as a scientific question.

Question 5

How do you make a comparison between two data sets?

Answer 5

You propose a relationship between them.

Question 6

What does H0 mean?

Answer 6

There is NO difference between the two data sets.

Question 7

What does H1 mean?

Answer 7

There is A difference between the two data sets.

Question 8

What does the null hypothesis mean?

Answer 8

There is NO DIFFERENCE between their means.

Question 9

What does the alternative hypothesis mean?

Answer 9

That there IS A DIFFERENCE between their means.

Question 10

What does a T score do?

Answer 10

Converts raw data into a standardised score when you do not know the population mean.

Question 11

What does the position of the standardised T score on the T distribution link to?

Answer 11

Relates raw data to likelihood of the occurence.

Therefore, allows the comparison of the data.

Question 12

What are the 3 main types of t - tests?

Answer 12

One Sample t - test
Paired t -test
Two sample t -test

Question 13

What is a one sample t - test?

Answer 13

Compares mean of a single sample to known or hypothesised population mean.

Question 14

What is a paired t - test?

Answer 14

Compares difference between two samples to hypothesised difference.

Question 15

What is a two sample t - test?

Answer 15

Compares means of two samples.

Question 16

How can you tell if a data set is independent?

Answer 16

It is independent if the probability of A occurring DOES NOT influence the probability of B occurring.

Question 17

How can you tell if a data set is paired?

Answer 17

It is paired if there is a link between the two observations.

Question 18

What is standard error?

Answer 18

Standard deviation of the sample means where multiple samples are taken from the sample population 𝜎/√𝑛

Question 19

What does variance mean?

Answer 19

How far a data set is spread out (average of squared distances from the mean).

Question 20

What does the Levene’s test measure?

Answer 20

Determines whether the samples have equal variance.

Alongside this, it tests whether the two conditions have the same or different amounts of variability between scores.

Question 21

What happens if the samples have equal variance?

Answer 21

A standard t - test can be used.

Question 22

At what probability level is equal variance considered?

Answer 22

P > 0.05

Question 23

What is the p value?

Answer 23

Probability of obtaining an effect at least as extreme and the one in your sample data.

Question 24

When is the null hypothesis considered true?

Answer 24

When the sample difference is greater than the P = 0.05 (or whatever it is)
This assumes that there is NO difference.

Question 25

When is a two tailed test used?

Answer 25

There is NO difference between the groups.

Question 26

What is confidence intervals (CI)?

Answer 26

Gives measure of uncertainty of the estimated difference.

Question 27

What value is assumed a normal distribution?

Answer 27

Value of 1.96

Question 28

What happens if the 95% CI for the difference contains the value 0?

Answer 28

P value > 0.05

Question 29

What happens if <0.05 occurs?

Answer 29

Reject the null hypothesis and thus, there is a STATISTICALLY significant difference.