Statistical Testing

Question 1

What are statistical tests used for?

Answer 1

Stats tests are used to determine whether a difference or association/correlation found in a particular investigation is statistically significant

Question 2

Three Criteria for Choosing a Statistical Test

Answer 2

1. Looking for a difference or a correlation/association.
2. Is experimental design related (repeated measures or matched pairs) or unrelated (independent groups.
3. What is the level of measurement (ie type of data)?

Question 3

Table for Choosing a Stats Test (Mnemonic)

Answer 3

N O I
R I C
S C C 
W M S
R U P

Question 4

Nominal Data

Answer 4

Categories.

Each item can only appear in one category.

There is no order

Question 5

Ordinal Data

Answer 5

Placed in order and the intervals are subjective.

Data is collected on a numerical, ordered scale but intervals are variable.

Ordinal data lacks precision because it is based on subjective opinion rather than objective measures

Question 6

Interval Data

Why better than ordinal data?

Answer 6

Units of equal size.

Interval data is based on numerical scales that include units of equal, precisely defined size.

This includes counting observations in an observational study or any public unit of measurement.

Interval data is better than ordinal data because more detail is preserved as the scores are not converted to ranks