Measures of Spread

Question 1

How do you calculate the range?

Answer 1

Find the difference between the maximum and minimum score

Biggest data - Smallest data

Question 2

What are the 3 main measures of spread?

Answer 2

1) Range
2) Variance
3) Standard deviation

Question 3

What is one con of using the range to measure spread?

Answer 3

Range doesn’t always change for distributions
with different shapes

Question 4

How do you calculate the sample variance?

Answer 4

1) Calculate the mean of the data set

2) Calculate the deviation of each score from the mean

3) Square the deviation

4) Calculate the slightly adjusted average squared deviation (sum of squared dev / N-1)

Question 5

How do you calculate deviation to find sample variance?

Answer 5

1) Calculate the mean of the data set

2) Arrange the numbers in the data set in ascending order

3) Calculate the deviation of each number from the mean (how far each score is from the mean)

Question 6

How do you calculate the standard deviation?

Answer 6

1) Calculate the mean of the data set

2) Calculate the deviation of each score from the mean

3) Square the deviation

4) Calculate the slightly adjusted average squared deviation (sum of squared dev / N-1)

5) Calculate the SD by square rooting (sum of squared dev / N-1)

Question 7

When data is more spread out, the standard deviation is …?

Answer 7

Larger

Question 8

When data is more “concentrated”, the standard deviation is…?

Answer 8

Smaller