Exploring and Describing Data

Question 1

Define

Range

Answer 1

Range is the simplest (and least accurate) measure of spread. It is found by subtracting the lowest score from the highest score.

Question 2

Define

Quartiles

Answer 2

Quartiles split the data into 4 equal groups. These are used to calculate the Interquartile Range.

Question 3

Define

Interquartile Range (IQR)

Answer 3

A more accurate calculation of spread, found by splitting the data into four equal groups (quartiles) and then subtracting the first quartile (Q1) from the third quartile (Q3).

Question 4

Standard Deviation

Answer 4

The most accurate measure of spread, which measues the average distance of each score crom the mean. You find it using a calculator.

Question 5

Define

Outliers

Answer 5

Any score that is greater than or equal to 1.5 times the IQR outside the IQR itself:
Outlier ≤ Q1 (–/+) 1.5 × IQR

Question 6

How do you calculate outliers?

Answer 6

1. Calculate the IQR.
2. Multiply the IQR by 1.5.
3. Subtract this value from Q1. Any values less than this answer in the data set are outliers.
4. Add this value to Q3. Any values greater than this answer in the data set are outliers.

Question 7

Five-Number Summary

Answer 7

lower extreme, Q1, median (Q2), Q3, upper extreme

Question 8

What do box-and whisker plots show?

Answer 8

A five-number summary of data