Week 4

Question 1

Measures of Relative Standing: Percentiles

Answer 1

Designed to provide information about the position of particular values relative to the entire data set.

Question 2

Percentile

Answer 2

The p^th percentile of a set of observation is the value for which at most p percent of the observations are less than that value and at most (100-p)% are greater than that value.

Question 3

Quartiles

Answer 3

Question 4

Quintiles

Answer 4

• Refers to the 20th, 40th, 60th, and 80th percentiles.
• Divides the ordered data into fifths.

Question 5

Deciles

Answer 5

• Refers to the 10th, 20th, 30th, 40th, 50th, 60th , 70th, 80th and 90th percentiles.
• Divides the ordered data into tenths.

Question 6

Percentiles (Example)

Answer 6

Question 7

Interquartile Range

Answer 7

The quartiles can be used to create another measure of
variability, the interquartile range, which is defined as
follows:
Interquartile Range (IQR) = Q₃ – Q₁

Question 8

Two Measures of linear association

Answer 8

1/ Covariance: Describes the direction of the relationship between two variables.

2/ Coefficient of Correlation: Describes how strong is the linear relationship between two variables?

Question 9

Covariance

Answer 9

However, it is often difficult to determine whether a particular covariance is large or small.

Question 10

Coefficient of Correlation

Answer 10

Question 11

Drawback of Coefficient of Correlation

Answer 11

Question 12

Important Note

Answer 12

Question 13

The Least Squares Method (Practise)

Answer 13

Question 14

The Least Squares Method (Formula)

Answer 14