Wk 6 Part 2: Data Visualisation

Question 1

What is data visualisation?

Answer 1

To understanding quantitative data, first to visualise the distributions of the variables and relationships between them.

• Use SPSS

Question 2

What are 2 cautions with data visualisation?

Answer 2

1. If we look long and hard enough, then we will find a relationship that is “significant” by chance even if there are actually no relationships.
2. Don’t just look for any pattern - make it relevant to your research question

Question 3

When exploring the distribution of a single numeric variable (numeric variables), what are 4 features that we want to describe?

Answer 3

1. Location
2. Spread
3. Shape
4. Deviations from the overall pattern.

Question 4

What is the data visualisation for nominal variable?

Answer 4

Nominal variable –> Bar chart

Question 5

What is the data visualisation for scale variable?

Answer 5

1. Box plot
2. Histogram

Question 6

What are 5 features of histogram?

Answer 6

1. Histograms show the estimated density of the distribution for each bin of values.
   
   • A bin is a bar in a histogram
2. Good picture of location, spread and shape of a distribution
   
   • The direction of skewing is the tail
3. Useful for visualising large numbers of observations
4. Somewhat subjective (based on number of bins)
5. Difficult to compare >2 groups

Question 7

What are density plots?

Answer 7

Density plots show a line for the estimated density of the distribution at each value.

Question 8

What are 7 features of quartiles and percentiles?

Answer 8

1. 0.25 quantile = first quartile
2. 0.75 quantile = third quartile
3. Interquartile range = between first & third quartile
4. 0.50 quantile (or 50th percentile) = median
5. 0.00 quantile = minimum
6. 1.00 quantile = maximum
7. We can calculate other quantiles or percentiles from data too.

Question 9

What is the first quartile?

Answer 9

0.25 quantile

Question 10

What is the third quartile?

Answer 10

0.75 quantile

Question 11

What is the interquartile range?

Answer 11

between first & third quartile

Question 12

What is the median?

Answer 12

0.50 quantile (or 50th percentile)

Question 13

What is the minimum?

Answer 13

0.00 quantile

Question 14

What is the maximum?

Answer 14

1.00 quantile

Question 15

Boxplot shows the _____ quartiles

Answer 15

five

Question 16

What are 2 features of boxplots?

Answer 16

1. Gives summary of location, spread and shape
2. Good for comparing multiple distributions

Question 17

For categorical variables (nominal & ordinal), we use _____ to show counts or proportions.

Answer 17

bar charts

Question 18

What are spineplots?

Answer 18

Width of each bar is proportional to its group size