DataData

Data is information

Data handling is when we organise, display and try to

understand information.

Some children wanted to find out about the length of songs. They wanted to know how long most

songs were.

They listened to some songs and timed how long each one lasted

• 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

Here 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

Not very easy to understand is it?Not very easy to understand is it?

Let’s turn it into a graph...

Graph showing how many songs there were of each length

Length (in minutes)

Num

ber o

f son

gs

Oh dear.... That wasn’t much

help

Every song is different...

So how can we find out what sort of length is most common?

We’ll start by sorting it into a tally chart

We can group the data

Song length Number of songs

1 min 30 sec to1 min 59 sec

2 min 0 sec to 2 min 29 sec

2 min 30 sec to2 min 59 sec

3 min 0 sec to 3 min 29 sec

3 min 30 sec to3 min 59 sec

4 min 0 sec to4 min 29 sec

4 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

Remember how we tally in fives:

So how many does this tally show?

1818

Right, let’s get back to that tally chart...

... and change it into a frequency table

Frequency tableSong length Number of songs

1 min 30 sec to1 min 59 sec

2 min 0 sec to 2 min 29 sec

2 min 30 sec to2 min 59 sec

3 min 0 sec to 3 min 29 sec

3 min 30 sec to3 min 59 sec

4 min 0 sec to4 min 29 sec

4 min 30 sec to4 min 59 sec

Song length Number of songs

1 min 30 sec to1 min 59 sec 22 min 0 sec to 2 min 29 sec 12 min 30 sec to2 min 59 sec 23 min 0 sec to 3 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 sec

Tally chart

Well, that bit was easy!

Now let’s display the information in a pictogram

We’re going to use one CD to stand for 2 songs, like this:

Song length Number of songs

1 min 30 sec to1 min 59 sec 22 min 0 sec to 2 min 29 sec 12 min 30 sec to2 min 59 sec 23 min 0 sec to 3 min 29 sec 53 min 30 sec to3 min 59 sec 34 min 0 sec to4 min 29 sec 1

Now we can use those symbols to make a pictogram

1 min 30 sec to1 min 59 sec

2 min 0 sec to 2 min 29 sec

2 min 30 sec to2 min 59 sec

3 min 0 sec to 3 min 29 sec

3 min 30 sec to3 min 59 sec

4 min 0 sec to4 min 29 sec

What else do we need?

What else do we need?

Number of songs

Song

len

gth

= 2 songs

We can show the

same information in a graph:

We can show the

same information in a graph:

Num

ber o

f son

gs

Song length

6

4

2

8Which

length of song is the

most common?

3 min to

3 min 29 sec

3 min to

3 min 29 sec

This is called the

mode

This is called the

mode

Num

ber o

f son

gs

Song length

6

4

2

8True or false?

Most songs are between

3 and 4 minutes long.

TrueTrue

Grouping dataGrouping data

When you group data, you have to make 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.

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)