T - Tests

Question 1

What is the T- Test used for?

Answer 1

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

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

Question 2

What are the two main values used in spirometry?

Answer 2

FEV1 = FORCED EXPIRATORY VOLUME IN ONE SECOND.
Volume of air exhale forcibly from the lungs in one second.
FVC = FORCED VITAL CAPACITY.
Volume of air exhaled from the lungs when you take a breath and blow all the way out.

Question 3

Explain the key features of a normal distribution.

Answer 3

• Bell - Shaped Curve.
• Mean and Median are equal and located at the centre of the distribution.
• Predictable percentage falls within the 1, 2 or 3 standard deviations of the mean.

Question 4

What two measurements are used to judge a normal distribution curve?

Answer 4

• Mean

- Standard Deviation

Question 5

How can you tell something is LESS LIKELY to be normal for that population?

Answer 5

The more standard deviations a value is from the mean.

Question 6

z = (x-u)/ sigma

Explain this equation.

Answer 6

Z score = single value.
X = Individual Score
U = Test Mean
Sigma = Test Standard Deviation.

Question 7

What is statistical population?

Answer 7

• Complete set of possible observations.

- Researchers must define the population they are interested in.

Question 8

What is sample?

Answer 8

Set of observations taken from the population.

Question 9

What does a good sample allow you to do?

Answer 9

Contains the information that allows you to make conclusions about the population.

Question 10

What is a parameter?

Answer 10

Value / Characteristic of the whole population.

Usually fixed // maybe unknown or unknowable.

Question 11

What is a statistic?

Answer 11

Value calculated from sample data. (ie: sample mean).
Value may vary between samples.
Is observable.

Question 12

What is a point estimate?

Answer 12

Use of a sample statistic to estimate a population parameter.

Question 13

How do you work out the standard error?

Also known as the standard deviation of sample means

Answer 13

standard deviation / square root of number of samples.

Question 14

What happens as the n increases?

Answer 14

The standard deviation gets smaller.

Question 15

What is a one sample test?

Answer 15

When a statistical test can tell whether a sample is different from a population.

Question 16

What is the normal distribution?

Answer 16

The distribution of a parameter in a population.

Question 17

What is required to work out the z score?

Answer 17

The population mean and standard deviation.

Question 18

What is normally unknown / unknowable?

Answer 18

Mean and SD.

Question 19

What happens in a T - statistic where by the sample size increases?

Answer 19

Distributions get taller and thinner.

Question 20

When does the t distribution reach normal distribution?

Answer 20

Once the sample size exceeds 30.

Question 21

What does ‘v’ stand for?

Answer 21

Degrees of freedom.

Question 22

What is degrees of freedom?

Answer 22

The number of values in the final calculation of a statistic which are free to vary.

Question 23

How do you work out the degrees of freedom?

Answer 23

Sample Size - 1