Question

The goal of this part is to give you a chance to practice working through the steps of calculating variance. Use the table of scores (X values) below to complete the following calculations. Assume the data in the table represents a sample, not a population. Use the extra columns in the table to show your work.

X
20
22
18
15
21

Question 2.1 (0.5 points) – Calculate the deviation score for each x value

Question 2.2 (0.5 points) – Calculate the Sum of Squares (sum of the squared deviations)

Question 2.3 (0.5 points) – Calculate the Variance

Question 2.4 (0.25 points) – Calculate the Standard Deviation

Answer 1

Question 2.1 – Calculate the deviation score for each x value

Deviation score for each x value is computed by substracting mean value from x value. it is indicated by ( ) column.

Here is the updated table with deviation score for each x value.

Mean is average of all x values or provided data set. computed mean values and substitute in table.

x	Mean
20	19.2	0.8	0.64
22	19.2	2.8	7.84
18	19.2	-1.2	1.44
15	19.2	-4.2	17.64
21	19.2	1.8	3.24

Question 2.2 – Calculate the Sum of Squares (sum of the squared deviations)

In above table column with values , indicates the squared deviation. Here is sum of the squared deviations. substituting values form table column .

Question 2.3 – Calculate the Variance

It is given that data in table is sample.

Question 2.4 – Calculate the Standard Deviation

It is given that data in table is sample.