Drawing Cumulative Frequency Diagrams Flashcards

All 6 cards in this deck

On a cumulative frequency graph, at which value of the data variable is each cumulative frequency plotted?
e.g. class $20<t\le40$ with cumulative frequency $35$

At the upper class boundary, so plot $(40,\,35)$.

True or false? Cumulative frequency points are plotted at the midpoint of each class interval.

False. They are plotted at the upper end (upper class boundary) of each interval.

How should the plotted points on a cumulative frequency graph be joined?

With a smooth curve or with straight line segments (a cumulative frequency polygon) — either is accepted, and no part may have a negative gradient.

On a cumulative frequency graph, what goes on each axis?

The data variable (labelled, with units) on the horizontal axis; cumulative frequency on the vertical axis.

Where does a cumulative frequency graph start?
e.g. first class $0<w\le2$

At the lower boundary of the first class with cumulative frequency $0$, i.e. the point $(0,\,0)$.

What are the steps to draw a cumulative frequency graph from a grouped frequency table?
e.g. classes $0<w\le2$ (frequency 7) and $2<w\le4$ (frequency 21)

1. Work out the cumulative frequencies: $7$, $28$
2. Plot each one at the upper class boundary: $(2,7)$, $(4,28)$
3. Join the points with a smooth curve or line segments