Descriptive Statistics

Question 1

How to calculate percentage increase?

Answer 1

Increase=new number - original number
% increase = increase / original number x 100

Question 2

How to calculate percentage decrease?

Answer 2

Decrease = original number - new number
% decrease = decrease/original number x 100

Question 3

What is the mean?

Answer 3

• add all values and divide by how many there are
• most sensitive as outliers can distort the mean
• takes into consideration all values in a data set (more representative)
• can only be used with ordinal and interval data

Question 4

What is the median?

Answer 4

• arranges data from highest to lowest then find the middle value
• not affected by extreme scores so ideal when considering a data set that is heavily skewed
• not as sensitive as the mean as it doesn’t use all the data
• doesn’t reflect all scores in a data set

Question 5

What is the mode?

Answer 5

• most frequently occurring value in a data set
• can be used for categorical data unlike mean and median
• not distorted by extreme scores
• can be more than one mode so not always useful
• 2 modes = bi modal
• more than 2 = multi modal

Question 6

What is the range?

Answer 6

• subtracting the lowest score from the highest and adding 1
• easy to calculate
• takes into account extreme scores
• doesn’t show whether data is clustered or spread evenly around the mean

Question 7

What is standard deviation?

Answer 7

• looks at how far the scores deviate from the mean
• larger SD = data is very dispersed around the mean, p’s performed differently
• smaller SD = data is very concentrated around the mean, p’s performed similarly
• takes into consideration all the values in a data set and is a precise measurement
• can be easily distorted by an extreme value so data could be misrepresented