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Mean,
median and range
 There
are seven numbers on the number line. Drag them up or down
to see how this affects the mean, median and range of the
data set.
Can
you find ways to move the data points that keep the median
the same but change the mean?
Can you find ways to change the numbers that keep the mean
the same but change the median?
How do the mean and median change when you keep the points
in the same order but just change their positions on the
number line?
What happens if you drag the numbers way off to one extreme
or the other extreme?
By changing the numbers, can you construct data sets in
which the mean seems to be a typical value but the median
is not? Vice versa?
For what types of data sets, if any, is the mean not very
representative? When is the median not very representative?
Can you find a data set that has a mean of, for example,
50 and a median of 75?
Can you find a data set that has a mean twice as big as
the median?
Mean,
median, range and standard deviation
 As
above but also shows the standard deviation.
Box
and Whisker Plot
 There
are 12 numbers on the number line. Drag them up or down
to see how this affects the mean, median and range of the
data set. A boxplot is generated as the variables change.
The
boxplot consists of a box, whiskers and outliers. A line,
drawn at the median, transects the box. The lower edge of
the box is drawn at the first quartile and the upper edge
at the third quartile. The whiskers, the lines extending
from the top and bottom of the box, join the highest and
lowest values that occur in the regions 1.5 x interquartile
range above and below the third and first quartiles. All
values that fall outside these extremes, outliers, are plotted
individually using an open circle.
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The
Data Challenge
Five
numbers are shown on a number line. The aim is to make the
five numbers fit various criteria. Drag the pointers along
the number line to change the numbers.
 There
are four challenge levels:
1.
Select five numbers that add up to a target total.
2. Select five numbers that add up to a target total and
match a target range.
3. Select five numbers that add up to a target total, match
a target range and median.
4. Select five numbers that match a target range, median
and mean.
Use these buttons to choose the scale and show or hide the
total, range, median and mean.
The
number line can just be used to show how the mean and median
change when the numbers get bigger or smaller.
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Use
the slider to determine the number of slices in the pie
chart (from 3 to 10). 