Cumulative Frequency Flashcards

All 6 cards in this deck

What is cumulative frequency?

A running total of the frequencies — the number of values up to and including the upper end of each class.

In a cumulative frequency table, how should the class intervals be written?
e.g. original classes $0<t\le10$, $10<t\le20$, $20<t\le30$

Every interval starts at the lowest value: $0<t\le10$, $0<t\le20$, $0<t\le30$ (all 'less than or equal to' values).

What should the last cumulative frequency in a completed table equal?

The total frequency — the total number of items in the data set.

True or false? The cumulative frequency of a class is just the frequency of that class.

False. You add all the frequencies up to and including that class.

What are the steps to complete a cumulative frequency table from a grouped frequency table?
e.g. frequencies $5$, $8$, $12$

1. Copy the first frequency: $5$
2. Add the next frequency: $5+8=13$
3. Keep adding along the table: $13+12=25$ (last value = total)

What is a cumulative frequency graph used for?

Estimating the median, quartiles and interquartile range of grouped data, and the number of values above or below a given value.