Week 3

Question 1

What types of graph work with two categorical variables?

Answer 1

Contingency table
Grouped bar graph
Mosaic plot

Question 2

What types of graph work with two Numerical variables?

Answer 2

Scatter plot 
Line plot (space or time)

Question 3

What types of graph work with numerical explanatory variable and categorical response variable?

Answer 3

More complex plots of GLMS

Question 4

What types of graph work with Categorical explanatory variable and Numerical response variable?

Answer 4

Strip Chart
Box plot
Multiple histograms
Line plot (ordinal only)

Question 5

What are Stripcharts?

Answer 5

also known as one dimensional scatter plots

Question 6

When are stripcharts suitable?

Answer 6

These plots are suitable compared to box plots when sample sizes are small. Jittering is used to separate observations with equal value.

Question 7

What are line graphs when are they useful?

Answer 7

used to display quantitative values over a continuous interval or time period.

Question 8

What are the steps for making a good graph?

Answer 8

1. Show the data
2. Make patterns easy to see
3. Represent magnitudes honestly
4. Draw elements clearly

Question 9

Why is showing the data important?

Answer 9

• A good graph allows you to visualise the measurements and helps the eye see patterns in the data.
• Showing the data makes it possible to evaluate the shape of the distribution of data points and compare variation between groups.
• It helps you spot potential problems.

Question 10

How does one make patterns easy to see?

Answer 10

• Use colour to highlight trends
• Things to be compared should be adjacent.
• Keep the axes the same when comparing data across to plots.
• Remember the purpose is to communicate essential patterns. If the pattern is not clear, then try another approach.

Question 11

How does one Represent magnitudes honestly

Answer 11

• Length or area must be proportional to the quantities being displayed. The eye instinctively reads height and area as magnitudes.
• Humans are poor at reading areas.
• A bar graph musty always have a baseline at zero. Strip charts do not need a zero baseline.

Question 12

When should you use pie charts?

Answer 12

don’t

Question 13

What should you do to make sure your elements are draw clearly?

Answer 13

• Cleary label axes and always include units of measurements in the label. Text should be legible and in a simple font.
• Avoid chart junk that obscures patterns in the data
• Avoid putting too much information into one graph. Remember the purpose is to communicate essential patterns, not to cram all the data into one figure.