eM2 – Choosing statistics

Question 1

In terms of analysis, what are correlations?

Answer 1

Hypothesis tests to evaluate relationships between variables

Question 2

What are comparisons?

Answer 2

Hypothesis tests to evaluate differences between groups or populations

Question 3

What is quantitative data?

Answer 3

Numeric information about quantities - i.e height width etc.

Question 4

What is qualitative / categorical data?

Answer 4

Information that cannot be measured - i.e. gender, stages of disease etc.

Question 5

Give two types of quantitative data and an example for each:

Answer 5

Continuous: age

Counted (discrete): number of people with hypertension

Question 6

Give two types of qualitative data and an example for each:

Answer 6

Nominal: Gender

Ordinal: Fitness (not fit, quite fit, very fit)

Question 7

What is the difference between continuous and discrete data?

Answer 7

Continuous can be divided to finer and more precise levels.

Discrete data cannot be made more precise.

Question 8

What is nominal data?

Answer 8

Qualitative data containing individual categories that cannot be put in an implicit rank/order

Question 9

What is ordinal data?

Answer 9

Categories that have an implicit/natural order.

Question 10

What is normality in terms of statistical analysis?

Answer 10

Normality is a measure of central tendency and dispersion of data - i.e symmetric distribution with “well behaved tails”

Question 11

What is meant by left skewness?

Answer 11

Mean to the left of the peak, long tail in negative (decreasing) direction of curve

Question 12

What is meant by right skewness?

Answer 12

Mean to the right of the peak, long tail in positive (increasing) direction of the curve

Question 13

What is kurtosis?

Answer 13

The sharpness of a peak of a distribution curve

Question 14

What two factors do statistical tests rely on?

Answer 14

50% of values above and below mean - symmetrical

2/3rds of data within 1 SD from mean - normal distribution

Question 15

How to assess normality of data quantitatively?

Answer 15

Shapiro-Wilks test - n>50

Kolmogarov-Smirnof test - n<50

Question 16

What is descriptive statistics?

Answer 16

A method of categorising large data sets into a format easy to read (tangible).

Question 17

What is the mean?

Answer 17

μ = ( Σ Xi ) / N

Question 18

What is the median?

Answer 18

(n+1)/2 -th number in the data set.

Question 19

What is the mode?

Answer 19

Most frequent data entry.

Question 20

What is the standard deviation in a data set?

Answer 20

σ = sqrt[ Σ ( Xi – μ )^2 / N ]

A measure of how dispersed the data are from the mean.

Question 21

What is meant by dependant (paired) data?

Answer 21

When the data being collected is consistantly being collected from the same subject

Question 22

What is meant by parametric statistics?

Answer 22

When the data from the population are well described by the mean and SD - normally distributed.

Question 23

What is meant by non-parametric statistics?

Answer 23

When the data is not well described by the mean - non-normally distributed quantitative data.

note: non-parametric tests are used for qualitative data.

Question 24

Parametric, 2 groups, paired

Answer 24

Paired t-test

Question 25

Parametric, 2 groups, unpaired

Answer 25

Independant t-test

Question 26

Parametric, 3+ groups, paired

Answer 26

Repeated measures, one way ANOVA

Question 27

Parametric, 3+ groups, unpaired

Answer 27

one way ANOVA

Question 28

Non-parametric, 2 groups, paired

Answer 28

Wilcoxon Signed Rank test

Question 29

Non-parametric, 2 groups, unpaired

Answer 29

Mann-Whitney U test

Question 30

Non-parametric, 3+ groups, paired

Answer 30

Kruskall-Wallis test

Question 31

Non-parametric, 3+ groups, unpaired

Answer 31

Friedman test

Question 32

To test for a linear relationship in a normally distributed population:

Answer 32

Pearson’s Correlation test

Question 33

To test for a linear relationship in a non-normally distributed population:

Answer 33

Spearman’s Correlation test