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6.4 Collecting data

6.4 Collecting data

You can use a frequency table or data-collection sheet to record grouped or ungrouped discrete data
and grouped continuous data. If you are grouping data, it is helpful to use equal class intervals.

If, for example, you were collecting data about the number Goals scored Tally Frequency
of goals scored per match by a football team, your data-collection 0
sheet may look like this. #e data values are only likely to vary 1
between 0 goals and maybe 4 goals, so there is no need to 2
3
group this data. 4
If you were collecting data about the number of points scored Goals scored Tally Frequency
per game by a netball team, your data-collection sheet may 0−9
look more like this. 10−19
#is time, the data values are likely to vary between 0 goals and 20−29
30−39
perhaps 50 goals, so you would group this data. 40−49
Always look at all the values the data can take, then decide whether you need to group the data.

Worked example 6.4

Here are the heights of 20 teachers, measured to the nearest centimetre.
1.71 m 1.66 m 1.82 m 1.74 m 1.62 m 1.76 m 1.57 m 1.79 m 1.75 m 1.69 m
1.65 m 1.77 m 1.80 m 1.52 m 1.75 m 1.60 m 1.72 m 1.85 m 1.59 m 1.88 m
a Put these heights into a grouped frequency table.
b Write down one conclusion that you can draw from the results on your data-collection sheet.

a The shortest teacher is 1.52 m and the tallest is
Height, h (m) Tally Frequency 1.88 m, so the values of the groups can range
1.50 ≤ h < 1.60 /// 3 between 1.50 m and 1.90 m. A range of 10 cm per
1.60 ≤ h < 1.70 //// 5 group is the best option, as the table is easy to
1.70 ≤ h < 1.80 //// /// 8 fill in and there are enough groups to be able to
1.80 ≤ h < 1.90 //// 4 compare the data.
TOTAL 20 Note that: ≤ means ‘less than or equal to’
< means ‘less than’.
b The group 1.70 ≤ h < 1.80 has the Look at the frequency column and make a comment
highest frequency. about the group with the highest or lowest frequency.

) Exercise 6.4

1 Xavier rolls a dice 30 times. These are the numbers he scores.
1 6 4 6 1 6 4 2 6 1 4 6 3 4 1
3 2 1 5 2 4 6 5 3 6 2 4 1 6 4
a Record this information on a data-collection sheet.
b Write down one conclusion that you can draw from the results on your data-collection sheet.
2 These are the points scored by a basketball team in 20 matches.
42 54 32 46 62 52 48 28 56 68
34 65 45 55 44 26 35 58 49 38

a Record this information on a data-collection sheet.
b Write down one conclusion that you can make from the results on your data-collection sheet.

6 Planning and collecting data 61