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# Grouping data

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### Grouping data

1. 1. DataDataData is informationData handling is when weorganise, display and try tounderstand information.
2. 2. Some children wanted to find outabout the length of songs. Theywanted to know how long mostsongs were.They listened to some songs andtimed how long each one lasted
3. 3. • 3min 20 seconds• 2 min 58 seconds• 3 min 12 seconds• 1 min 59 seconds• 4 min 03 seconds• 2 min 15 seconds• 3 min 32 secondsHere are their results:• 3min 37 seconds• 3 min 58 seconds• 1 min 45 seconds• 3 min 0 seconds• 3 min 13 seconds• 2 min 35 seconds• 3 min 17 seconds
4. 4. Not very easy to understand is it?Not very easy to understand is it?Let’s turn it into a graph...
5. 5. Graph showing how many songs therewere of each lengthLength (in minutes)NumberofsongsOh dear.... Thatwasn’t much help
6. 6. Every song is different...So how can we find out what sort oflength is most common?We’ll start by sorting it into atally chartWe can group the data
7. 7. Song length Number of songs1 min 30 sec to1 min 59 sec2 min 0 sec to2 min 29 sec2 min 30 sec to2 min 59 sec3 min 0 sec to3 min 29 sec3 min 30 sec to3 min 59 sec4 min 0 sec to4 min 29 sec4 min 30 sec to4 min 59 sec• 3min 20 seconds• 2 min 58 seconds• 3 min 12 seconds• 1 min 59 seconds• 4 min 03 seconds• 2 min 15 seconds• 3 min 32 seconds• 3min 37 seconds• 3 min 58 seconds• 1 min 45 seconds• 3 min 0 seconds• 3 min 13 seconds• 2 min 35 seconds• 3 min 17 seconds
8. 8. Remember how we tally in fives:So how many does this tally show?1818
9. 9. Right, let’s get back to that tally chart...... and change it into a frequency table
10. 10. Frequency tableSong length Number of songs1 min 30 sec to1 min 59 sec2 min 0 sec to2 min 29 sec2 min 30 sec to2 min 59 sec3 min 0 sec to3 min 29 sec3 min 30 sec to3 min 59 sec4 min 0 sec to4 min 29 sec4 min 30 sec to4 min 59 secSong length Number of songs1 min 30 sec to1 min 59 sec 22 min 0 sec to2 min 29 sec 12 min 30 sec to2 min 59 sec 23 min 0 sec to3 min 29 sec 53 min 30 sec to3 min 59 sec 34 min 0 sec to4 min 29 sec 14 min 30 sec to4 min 59 secTally chart
11. 11. Well, that bit was easy!Now let’s display the information in a pictogram
12. 12. We’re going to use one CD to stand for 2 songs, like this:Song length Number of songs1 min 30 sec to1 min 59 sec 22 min 0 sec to2 min 29 sec 12 min 30 sec to2 min 59 sec 23 min 0 sec to3 min 29 sec 53 min 30 sec to3 min 59 sec 34 min 0 sec to4 min 29 sec 1
13. 13. Now we can use those symbols to make a pictogram1 min 30 sec to1 min 59 sec2 min 0 sec to2 min 29 sec2 min 30 sec to2 min 59 sec3 min 0 sec to3 min 29 sec3 min 30 sec to3 min 59 sec4 min 0 sec to4 min 29 secWhat else dowe need?What else dowe need?Number of songsSonglength= 2 songs
14. 14. We canshow thesameinformationin a graph:We canshow thesameinformationin a graph: NumberofsongsSong length6428Whichlength ofsong is themostcommon?3 minto3 min 29sec3 minto3 min 29secThis iscalled themodeThis iscalled themode
15. 15. NumberofsongsSong length6428True orfalse?Most songsare between3 and 4minutes long.TrueTrue
16. 16. Grouping dataGrouping dataWhen you group data, you have tomake all the groups equal.In this example, all the groups were 30 seconds long.The same rule applies to any grouped data.If we were grouping tables test scores, we could use:0-10, 11-20, 21-30, 31-40 and so on.
17. 17. What have we learned?What have we learned?• How to group data• How to make a tally chart• How to make a frequency table• How to make a pictogram• How to make a graph (bar chart)• How to group data• How to make a tally chart• How to make a frequency table• How to make a pictogram• How to make a graph (bar chart)