Measures Of Dispersion

Question 1

Strength of the range as a descriptive statistic

Answer 1

Identifies how spread out the data is because it accounts for the end values of the data set

Question 2

Limitations of the range as a descriptive statistic

Answer 2

Is affected by extreme values because values at the highest and lowest end of set are used and these may not actually reflect the data set accurately

Fails to take into account the distribution of the numbers, meaning it does not indicate whether most numbers are closely grouped around the mean or spread evenly

Question 3

Steps to calculate a standard deviation

Step 1: Find the __

Step 2: __ the __ from each score

Step 3: __ each deviation

Step 4: __ the squared deviations

Step 5: __ the __ by the number of scores

Step 6: Take the __ __ of the result from Step 5

Answer 3

Step 1: Find the mean

Step 2: Subtract the mean from each score

Step 3: Square each deviation

Step 4: Add the squared deviations

Step 5: Divide the sum by the number of scores

Step 6: Take the square root of the result from Step 5

Question 4

Strengths of standard deviation

Answer 4

Is a precise measure of dispersion because all the values are taken into account, this means we know whether values are closely grouped around the mean or spread out

Not as affected by extreme values

Question 5

Weakness of standard deviation

Answer 5

May hide characteristics of the data like extreme values