Basic Statistics

Question 1

Nominal Scale

Answer 1

Observations are placed in one category or another. Can create frequency tables but cannot do any other maths.

Question 2

Ordinal Scale

Answer 2

Allows scores to be ranked, but there is no indication of differences between the ranks.

Question 3

Interval Scale

Answer 3

Scores can be ranked and there are equal intervals between each rank.

Question 4

Ratio Scale

Answer 4

Scores are ranked, have equal intervals and there is an absolute zero point.

Question 5

Measures of Central Tendency

Answer 5

Mean (average), median (middle score) and mode (most common score). Mean is most useful.

Question 6

Measures of Variability

Answer 6

Range (spread of scores), average deviation (sum of difference between each score and the mean divided by n) and standard deviation (square root of the variance). SD is most useful.

Question 7

Skewness

Answer 7

Whether most scores fall towards the high end (negative) or low end (positive) of the distribution.

Question 8

Kurtosis

Answer 8

The steepness of the curve. Platykurtic - flat curve, Leptokurtic - peaked curve, Mesokurtic - normal curve.

Question 9

Normal Distribution

Answer 9

Theoretical bell-shaped curve where the mean, median and mode are equal.

Question 10

Standard Scores

Answer 10

Raw scores that have been adjusted from one scale to another to fit a normal distribution (z-scores, t-scores, stanines)

Question 11

Norms

Answer 11

Performances defined by groups (age, education etc) on a test that are then used to standardise a test. Compare results on a test to the standardised scores gained from the normative sample.

Question 12

Correlation

Answer 12

Expression of the strength and direction of the relationship between two variables.

Question 13

Regression

Answer 13

Analysis of the relationship between two or more variables for the purpose of understanding how one variable can predict another.