1/02/
Numerical data
Frequency tables & Histograms
Learning goal: To construct frequency
distribution tables for numerical data.
Numerical – Discrete -­‐‑ Ungrouped
Numerical – Discrete -­‐‑ Grouped
Numerical – Continuous -­‐‑ Grouped
Frequency tables
Height (cm)
Frequency
8-­‐‑
3
9-­‐‑
3
10-­‐‑
9
11-­‐‑
4
12-­‐‑
4
13-­‐‑
1
14-­‐‑
1
Height (cm)
Frequency
8-­‐‑
3
9-­‐‑
3
10-­‐‑
9
11-­‐‑
4
12-­‐‑
4
13-­‐‑
1
14-­‐‑
1
1/02/
Histograms
Summary
•  Discrete data
o  Be careful when making class intervals that they do not overlap.
o  E.g. 0, 1, 3, 0, 1, 7, 6, 6, 8, 1, 9, 5, 2, 2, 7.
o  Group size = 5 -> 0 – 4, 5 – 9, …
•  Continuous data
o  Groups/classes are written like this:
o  115-, 120-, 125-, …
o  115- includes numbers from 115 to 119.999…
•  Histogram - Just like a bar chart with some
exceptions:
o
o
o
o
No gap between each column
Leave ½ column gap at the start and end
Ungrouped data -> label in the centre
Grouped data -> label either side