RM - Introduction to statistical testing

Question 1

What are the 2 types of statistics?

Answer 1

Descriptive and inferential.

Question 2

What are examples of descriptive statistics?

Answer 2

Averages and graphs.

Question 3

What are the 2 key issues with using inferential statistics?

Answer 3

To make the inference we have to use statistical (inferential) tests that have been designed to work out the probability (p) of whether a particular set of data could simply have occurred by chance.

We may have found a difference between the two samples, but is the difference big enough? It is extremely unlikely that, on average, the any two groups of people will perform identically. Therefore we need a test to establish whether the difference is big enough to be of significance.

Question 4

What type of hypothesis is a ‘one-tailed test’ used for?

Answer 4

A directional hypothesis.

Question 5

What type of hypothesis is a ‘two-tailed test’ used for?

Answer 5

A non-directional hypothesis.

Question 6

What type of test is used to study a directional hypothesis?

One or two-tailed?

Answer 6

A ‘one-tailed test’.

Question 7

What type of test is used to study a non-directional hypothesis?
One or two-tailed?

Answer 7

A ‘two-tailed test’.

Question 8

Give an example of a statistical test:

Answer 8

Sign test.

Question 9

What 3 things do we need to know about the sign test?

Answer 9

When it is appropriate to use a sign test.
How to do the sign test.
How to report the conclusion that can be drawn.

Question 10

When is a sign test used?

Answer 10

When looking at paired or related data.
The 2 related pieces of data could come from a repeated measures design. (The same person tested twice).
Can also be used with matched pairs design because the participants are paired and therefore count, for the purposes of statistics, as one person tested twice.

Question 11

What are the steps in carrying out a sign test?

Answer 11

State the hypothesis.
Record the data and work out the sign.
Find calculated value (S).
Find critical value of S.
Check if the result is in the right direction.

Question 12

What happens in the first step of the sign test?

State the hypothesis:

Answer 12

Choosing a hypothesis and stating if it is directional or non-directional and which type of test will be used (one-tailed or two-tailed).

Question 13

What happens in the second step of the sign test?

Record data and work out the sign:

Answer 13

Record each pair of data and record a minus (-) for a decrease in the result and a plus (+) for an increase in the result.

Question 14

What happens in the third step of the sign test?

Find calculated value:

Answer 14

Add up the pluses and add up the minuses and selecting the smaller value. This is what S is equal to. (The S value).

Question 15

What is the symbol for the test statistic we are calculating?

Answer 15

S

Question 16

What does the symbol S mean in the sign test?

Answer 16

The test statistic we are calculating.

Question 17

What happens in the fourth step of the sign test?

Find critical value of S:

Answer 17

Using the table of critical values, locate the column headed 0.05 for one-tailed tests or the 0.1 column for two-tailed tests. Read down and select the row corresponding to the N value of the results you have.

Question 18

What is N in the sign test?

Answer 18

The total number of scores ignoring any zero values (those which had no change in results).

Question 19

What happens in the fifth step of the sign test?

Check if the result is in the right direction:

Answer 19

If the hypothesis is directional we have to check that the result is in the expected direction.

If this was the case then we can accept the hypothesis.

Question 20

How can we tell if a result is significant in the sign test?

Answer 20

Calculated values of S must be equal to or less than the critical value in the table for significance to be shown.

Question 21

What value do we select for the level of significance in the sign test?

Answer 21

0.05 or 5% (in most cases).

Question 22

What is a calculated value?

Answer 22

The value of a test statistic calculated for a particular data set.

Question 23

What is the critical value?

Answer 23

In an inferential test the value of the test statistic that must be reached to show significance.

Question 24

What is a one-tailed test?

Answer 24

Form of test used with a directional hypothesis.

Question 25

What is probability (p)?

Answer 25

A numerical measure of the likelihood or chance that certain events will occur.

Question 26

What is the sign test?

Answer 26

A statistical (inferential) test to determine the significance of a sample of related items of data.

Question 27

What is significance?

Answer 27

A statistical term indicating that the research findings are sufficiently strong for us to accept the research hypothesis under test.

Question 28

What is the table of critical values?

Answer 28

A table that contains the numbers used to judge significance. The calculated value of the test statistic is compared to the number in the table (called the critical value) to see if the calculated value is significant.

Question 29

What is a test statistic?

Answer 29

A statistical test is used to calculate a numerical value. For each test this value has a specific name such as S for the sign test.

Question 30

What is a two-tailed test?

Answer 30

Form of test used with a non-directional hypothesis.

Question 31

What is a type 1 error?

Answer 31

False positive result - accepting the alternate when you should’ve accepted the null.

Question 32

What is a type 2 error?

Answer 32

False negative - accepting the null when you should’ve accepted the alternate.