Math Tech IIII, Oct 8
Constructing Dot Plots, Understanding
Pictographs
Book Sections: 2.2
Essential Questions: What are more descriptive statistical
representations and how do I construct and use them?
Standards: DA-4.1, DA-4.2, DA-4.3
The Pictograph
• A Pictograph uses pictures or illustrations to
show how specific quantities compare.
• Each symbol represents a convenient number
of items to display the date.
• Pictographs are usually a variation on the
frequency graph where the pictures are in-place
of the frequency towers.
Example 1 of a Pictograph
Example 2 of a Pictograph
Example 3 of a Pictograph
Pictograph Tidbits
• Pictographs have been around for a long time.
Cave drawings over 3000 years old have shown
them, and in more than one culture.
• This drawing can be a way of simplifying data
by showing that data in a multidimensional way
via pictures.
• The
most frequently used misleading display
is the pictograph.
Drawing a Pictograph
We will leave pictographs to the graphic designers of the world and
keep ourselves to how they are used and why they are used.
Dot Plots
•A Dot Plot is a very simple way of displaying
the distribution of a smaller set of data using a
number line that covers the range of the data
and dots to represent individual points.
• This display shows you any distribution
patterns, clusters of data, the range of the data,
and any possible outliers that might be a part of
the data set.
Example of a Simple Dot Plot
Examples of a Dot Plots
Example of a Dot Plot w/Outlier
The Limits of a Dot Plot
• Too much data and too wide of a range are dot
plot killers.
• Too much data – 200 data points is probably
too much for a dot plot. The best examples
usually have between 30 – 75 points.
• Too much range – to be good display, a dot
plot is seen at once. If your data range exceeds
a good number line, your dot plot is doomed.
Drawing a Dot Plot
Step 0 – Determine range of data (Hi Value – Lo Value). Sorting
data from least to greatest may help to identify the values you need.
Step 1 – Select a number line with the range of the data. Each
mark should be ONE value, unless there is no other way to fit it in.
Step 2 – Label some values (start, end, every 5 or 10, as
appropriate) to make it easy to plot dots.
Step 3 – Plot dots on value positions on the number line. If a
duplicate value occurs, plot a second (or however many) dot above
previous dots at a value.
Step 4 – Label graph purpose
Example 1
At High on The Hill store, management kept track of sales during a recent
workday. Make a dot plot of the data:
$1426, $1426, $1420, $1419, $1417, $1411, $1412, $1419, $1412, $1423,
$1414, $1416, $1418, $1427, $1416, $1414, $1411, $1421, $1426, $1413,
$1421, $1416, $1418, $1422, $1418, $1427, $1422
Example 1
At High on The Hill store, management kept track of sales during a recent
workday. Make a dot plot of the data:
$1426, $1426, $1420, $1419, $1417, $1411, $1412, $1419, $1412, $1423,
$1414, $1416, $1418, $1427, $1416, $1414, $1411, $1421, $1426, $1413,
$1421, $1416, $1418, $1422, $1418, $1427, $1422
Example 2
We Sit For You is a babysitting service in a mall. For a month, they kept track of
the number of babies they were left with. Make a dot plot of the data:
35, 43, 43, 31, 32, 37, 37, 32, 45, 38, 43, 36, 31, 40, 42, 36, 41, 41, 44, 31, 31,
31, 31, 32, 43, 40, 33, 34, 44, 42
Example 2
We Sit For You is a babysitting service in a mall. For a month, they kept track of
the number of babies they were left with. Make a dot plot of the data:
35, 43, 43, 31, 32, 37, 37, 32, 45, 38, 43, 36, 31, 40, 42, 36, 41, 41, 44, 31, 31,
31, 31, 32, 43, 40, 33, 34, 44, 42
Hi = 45
Lo = 31
Example 3
If you have to go by two’s on the scale, what do you do?
Class work: Classwork Handout 1-4
Homework: None