Methodology: Stats

Question 1

What are descriptive statistics?

Answer 1

Ways of summarising data from research.

Question 2

Give an example of a descriptive statistic.

Answer 2

A graph such as a bar chart or frequency distribution.

Question 3

What are the measures of central tendency?

Answer 3

• Mean
• Median
• Mode

Question 4

Define ‘mean’.

Answer 4

The average result from a number of scores.

Question 5

How is a mean calculated?

Answer 5

Adding data together and dividing by the number of scores there are.

Question 6

Define ‘median’.

Answer 6

The number in the middle of a data set with as many scores above as it has below.

Question 7

How is a median calculated?

Answer 7

By listing values in a data set in order of size and finding the middle.

Question 8

What do you do if there are two medians?

Answer 8

Calculating the mean of the two central numbers by adding them together and dividing by 2.

Question 9

Define ‘mode’.

Answer 9

The most frequently occurring piece of data.

Question 10

What names are given when data has 2, 3, or 4 modes.

Answer 10

2 - bimodal
3 - trimodal
4 - multimodal

Question 11

How is a mode calculated?

Answer 11

Looking for the most frequently appearing value in a data set.

Question 12

How might a mean calculate a misleading figure?

Answer 12

There may be few extremes or an anomaly in the data that would skew the mean.

Question 13

What are the measures of dispersion?

Answer 13

• Range

- Standard deviation

Question 14

Define ‘range’.

Answer 14

The difference between the largest and smallest value in a data set.

Question 15

How is a range calculated?

Answer 15

By taking the smallest number away from the largest.

Question 16

Define ‘standard deviation’.

Answer 16

The average distance between values of a data set around a mean.

Question 17

What does a large standard deviation indicate?

Answer 17

That the scores are widely dispersed in relation to the mean.

Question 18

What does a small standard deviation indicate?

Answer 18

That the scores are closer to the mean.

Question 19

Identify the 6 steps to working out standard deviation.

Answer 19

1) Find the mean of a data set
2) Minus the mean from each value in the data
3) Square each new value
4) Add all the squared values together
5) Divide the total by number of scores -1
6) Square root that value

Question 20

Define ‘frequency’.

Answer 20

The number of times a particular event or piece of data occurred.

Question 21

How are frequencies displayed?

Answer 21

On a frequency distribution curve.

Question 22

Describe the shape of a normal distribution.

Answer 22

A bell curve.

Question 23

What are the two types of descriptive statistical data that can be found in a frequency distribution?

Answer 23

• Central tendencies

- Measures of dispersion

Question 24

Describe the features of a normal distribution of central tendencies.

Answer 24

• The mean, median, and mode all occur at the same point with the same value
• It has the same shape either side of the mean as the pattern of values is exactly the same above and below the median

Question 25

Describe the features of a normal distribution of measures of dispersion.

Answer 25

• Knowing the mean and the standard deviation of scores on a normal distribution allow us to work out what scores fall within certain limits
• The proportion of scores falling above or below the mean (the centre) by 1 standard deviation is 34%
• The proportion of scores falling above or below the mean (the centre) between 1 and 2 standard deviations is 13.6%
• The proportion of scores falling above or below the mean (the centre) by 2 standard deviations is 2.4%

Question 26

What are the two alternatives to a normal distribution?

Answer 26

• Positive skew

- Negative skew

Question 27

Describe the features of a positive skew distribution.

Answer 27

• The mode is the highest point, then the media, then the mean and gets small the higher it is on the Y axis and lower on the X axis
• It is due to extremely high scores that affect the mean

Question 28

Describe the features of a positive skew distribution.

Answer 28

• The mode is the highest point, then the media, then the mean and gets small the higher it is on the X axis and lower on the Y axis
• It is due to extremely low scores that affect the mean

Question 29

What does a skewed distribution show?

Answer 29

That there is a large spread of data due to an anomaly.

Question 30

List the 4 types of hypothesis tests.

Answer 30

1) Wilcoxen Signed Ranks Test
2) Mann Whitney U Test
3) Chi-Squared Test
4) Spearman’s Rho Correlation

Question 31

Define ‘nominal data’.

Answer 31

Categories that are not measured or ordered.

Question 32

Define ‘ordinal data’.

Answer 32

Values that have ranks.

Question 33

Define ‘interval/ratio data’.

Answer 33

Measuring the distance between attributes/there is always an absolute zero.

Question 34

Why are inferential statistics used?

Answer 34

To determine the significance of data or whether it was simply due to chance.

Question 35

What level of significance do Psychologists use?

Answer 35

0.05, a 95% chance that results aren’t due to chance.

Question 36

Describe the conditions for which to use a Wilcoxen Signed Ranks Test.

Answer 36

• Testing a difference
• Repeated measures
• Ordinal data

Question 37

Describe the conditions for which to use a Mann Whitney U Test.

Answer 37

• Testing a difference
• Independent measures
• Ordinal data

Question 38

Describe the conditions for which to use a Chi-Squared Test.

Answer 38

• Testing a difference
• Independent measures
• Nominal data

Question 39

Describe the conditions for which to use a Spearman’s Rho Correlation.

Answer 39

• Testing a relationship

- Ordinal/interval data