Descriptive statistics

Question 1

What does the symbol ∑ mean?

Answer 1

sum of multiple terms

Question 2

What is a frequency distribution?

Answer 2

• tables that report the number of cases in each category of a variable
• allow us to calculate frequency, percentage, mean and proportion of variable

Question 3

What are cumulative frequencies?

Answer 3

• cumulative frequency lists the total number of cases falling at a particular score or below it in the distribution
• cumulative percentage: lists the total percentage of cases falling at a particular score or below it in the distribution
  –> only useful for ordinal/interval-ratio variables

Question 4

What is a percentage?

Answer 4

standardise raw data to a base of 100
Percentage= Proportion x 100

Question 5

what are proportions?

Answer 5

standardise raw data to a base of 1.00
proportion= Percentage ÷ 100

Question 6

What are percentages and proportions useful for?

Answer 6

Comparing groups of different size in terms of similarities or differences

Question 7

What is an appropriate way to graphically present nominal or ordinal variables?

Answer 7

• Pie graphs: display the percentages of a variable’s categories
• bar graph: effective for displaying the relative frequencies for 2 or more categories of a variable

Question 8

What graphic presentation for interval ratio is appropriate?

Answer 8

Histograms: like bar graphs but the sides of the bars touch creating a continuous series