# 2Tvwo § 2.6 Grouping data '19'20

§2.6 Grouping data
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Slide 1: Tekstslide
WiskundeMiddelbare schoolhavo, vwoLeerjaar 2

In deze les zitten 11 slides, met tekstslides. Lesduur is: 50 min

## Onderdelen in deze les

§2.6 Grouping data

#### Slide 1 -Tekstslide

Grouping data
If you try to put the data below into a frequency table, you will get a very large table, with a lot of frequencies of 0 and 1.

To get a more useful frequency table,
you can group data.

#### Slide 2 -Tekstslide

Grouping data
Instead of counting the frequency of every separate value, you make groups of values, called class intervals.
Each class interval is the same size

Notice that 7.0 belongs in
the class interval from 7 to 8,
NOT from 6 to 7.

#### Slide 3 -Tekstslide

Modal class
When you have a frequency table with
grouped data, you do not talk about the
mode, but about the modal class.
This is the class interval with the
highest frequency.

Here the modal class is from 7 to 8.

#### Slide 4 -Tekstslide

Midpoint
To calculate the mean from a frequency table with grouped data, you first calculate the midpoints of each group. This is the mean of the class boundaries.

midpoint from 3 to 4: (3 + 4)/2 = 3.5
midpoint from 4 to 5: (4 +5)/2 = 3.5
etc.

#### Slide 5 -Tekstslide

Do you know what 'dirty data' means?
It is WRONG INFORMATION.
See next slide for more!

#### Slide 7 -Tekstslide

Mean
Calculating the mean from a frequency table with grouped data is very similar to the method for a normal frequency table.
- multiply the frequency with the midpoint for each class interval
- divide the total of the multiplications by the total of the frequencies

Mean

#### Slide 9 -Tekstslide

Doing a chapter on Statistics ...
asks a certain TEMPO from you,
dealing with many data in one way or other!
Most tasks are not that difficult,
but just a lot of work.