Tables
Most reports and publications use tables to present some information. Such tables often have several rows and columns and may extend over two or more pages, but we initially restrict attention in this section to much simpler tables.
Frequencies
One common type of data is a set of frequencies (or counts) that describe how many items from some group (often people, households, farms or companies) are in each of a set of non-overlapping categories. A table of these frequencies is called a frequency table.
Rice survey
As part of a survey of rice producers in Sri Lanka, 36 farmers were randomly selected from 4 villages. Each sampled farmer was asked about the variety of rice that he used and the varieties were categorised into 'Old', 'Traditional' or 'New'. The 36 resulting categorical values are shown on the left of the diagram below.
To calculate the frequencies for each of the three types of rice by hand, you would work through the table of values, drawing a line against the appropriate category name for each value (a tally). These tallies would be finally be added to give the frequencies.
Click on each of the categorical values in turn to illustrate how the tallies and frequencies are obtained.
The final table of frequencies on the right summarises usage of the three types of rice. The frequency table contains all information about the distribution of rice types.
Drivers killed in New Zealand
The following three frequency tables describe different characteristics of the 190 drivers who were killed in road accidents in New Zealand during 2006.
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Each driver who was killed contributes 1 to exactly one category in each frequency table.
Ethnic groups
Most frequency tables in official statistics publications describe much larger populations of items. The frequency table below describes the ethnic groups of the New Zealand population as specified in the 2001 Census.
Ethnic group | Frequency |
---|---|
European Maori Pacific peoples Asian Other Not stated or unidentifiable |
2,868,009 526,281 231,798 237,459 24,924 150,546 |
Total | 3,737,277 |
Tanzania drinking water
The next frequency table categorises households rather than individuals. It shows the main source of drinking water for all rural households in Tanzania in the dry season of 2002/3.
Source of drinking water | Frequency |
---|---|
Piped water Protected well Protected spring Unprotected well Unprotected spring Surface water Rainwater catchment Other |
1,093,185 653,451 191,042 1,307,623 701,233 754,539 76,989 27,253 |
Total | 4,805,315 |