2. Often when you encounter histograms, you have a pretty
good understanding of what they’re trying to tell you.
Sometimes though, depending on your position and the
situation, you may encounter a histogram that deals with
things outside your expertise. At that point, you have to
interpret and understand the story the data is telling you.
Website Visit Duration Histogram
25
Number of visits
20
15
10
5
0
Visit Duration in Minutes
3. Interpreting the data or the histogram means taking what
you see and changing it into something that is usable in for a
business decision. It’s harder that it looks. You will need the
following:
1. Understanding of histograms
2. Looking for inconsistencies
Website Visit Duration Histogram
25
Number of visits
20
15
10
5
0
Visit Duration in Minutes
5. This table of data is the backend set of data that fuels the
histogram to the right. Notice how the differences in
numbers would be very hard to capture by using a bar chart.
Visit
Duration Bin
1.5 0
1.8 1
5.2 2
4.4 3
6.1 4
2.1 5
Knowing what a histogram looks like on the backend is huge
0.3 6
1.3 7
1.1 8
6.4 9
3.8 10
2.7
2.4
in understanding how it looks on the front end.
2.6
3.1
1.3
1.2
1.4
1.5
0.9
5.9
4.9
9.1
2.1
1
Visit Duration 1.6
0.2
0.3
4.5
1.5 5.9 1.4 0.9 2.3 4.9
3.8
1.7
1.8 4.9 1.2 4.1 4.2
Website Visit Duration Histogram
2.1
0.8
0.1
3.2
5.2 9.1 5.2 3.1 3.2 0.7
1.1
4
7.6
4.4 2.1 3.4 6.4 3.1 25
1.4
1.2
5.2
6.1 1 3.2 3.1 5.5
3.4
Number of visits
3.2
20 4.1
1.5
2.1 1.6 4.1 4.1 0.7 8.9
3.6
4.1
0.3 0.2 1.5 5.9 0.9 15 2.4
0.4
1.7
3.5
1.3 0.3 8.9 6.2 3.1 10 2.4
2.2
2.8
2.9
1.1 4.5 3.6 0.4 1.7 5 1.9
0.3
0.9
4.1
6.4 4.9 4.1 3.5 1.1 0
3.1
6.4
3.1
4.1
3.8 3.8 2.4 7.6 1 5.9
6.2
0.4
3.5
2.7 1.7 0.4 0.1 2.1 7.6
0.1
8.3
2.4 2.1 1.7 8.3 1.9 9
1.1
0.9
0.3
2.6 0.8 3.5 9 3.1 6.2
7.9
1
2.3
3.1 0.1 2.4 1.1 0.9 4.2
3.2
3.1
1.3 3.2 2.2 0.9 1.1 5.5
0.7
Visit Duration in Minutes
0.9
3.1
1.2 0.7 2.8 0.3 3.7 1.7
1.1
1
2.1
1.4 1.1 2.9 6.2 1.9 1.9
3.1
0.9
1.1
1.5 4 1.9 7.9 3.7
1.9
0.9 7.6 0.3 1
6. The second part to data interpretation is looking for
inconsistencies. Knowing what a histogram should look like
is helpful in finding what is out of the ordinary. While most
Visit
Duration Bin
1.5 0
1.8 1
5.2 2
4.4 3
6.1 4
2.1 5
histograms roughly follow a standard distribution curve,
0.3 6
1.3 7
1.1 8
6.4 9
3.8 10
2.7
2.4
that might not always be the case. The histogram below is
2.6
3.1
1.3
1.2
1.4
1.5
0.9
5.9
“skewed” to the left. In other cases, to see skewing might be
4.9
9.1
2.1
1
1.6
0.2
0.3
a red flag, but in the case of website visits, the majority of
4.5
4.9
3.8
1.7
2.1
0.8
0.1
3.2
which are often short, this might actually be normal.
0.7
1.1
4
7.6
1.4
1.2
5.2
3.4
3.2
4.1
1.5
8.9
3.6
4.1
2.4
Website Visit Duration Histogram
0.4
1.7
3.5
2.4
2.2
2.8
2.9
1.9
0.3
25 0.9
4.1
3.1
Number of visits
6.4
20 3.1
4.1
5.9
6.2
0.4
15 3.5
7.6
0.1
8.3
10 9
1.1
0.9
0.3
5 6.2
7.9
1
2.3
4.2
0 3.2
3.1
5.5
0.7
0.9
3.1
1.7
1.1
1
2.1
1.9
3.1
0.9
1.1
3.7
1.9
Visit Duration in Minutes
7. When interpreting a histogram, especially for data sets that
you don’t normally deal with, it is helpful to get historical
data sets and see how they stack up with the present Visit
Duration
1.5
1.8
5.2
4.4
Bin
0
1
2
3
histogram. If peaks or valleys are present on the current
6.1 4
2.1 5
0.3 6
1.3 7
1.1 8
6.4 9
3.8 10
2.7
histogram where there weren’t in historical data, it might
2.4
2.6
3.1
1.3
1.2
1.4
1.5
indicate an inconsistency. Using historical data will help you
0.9
5.9
4.9
9.1
2.1
1
1.6
0.2
develop an idea of what the histogram should look like
0.3
4.5
4.9
3.8
1.7
2.1
0.8
before seeing it.
0.1
3.2
0.7
1.1
4
7.6
1.4
1.2
5.2
3.4
3.2
4.1
1.5
8.9
3.6
4.1
Website Visit Duration Histogram
2.4
0.4
1.7
3.5
2.4
2.2
2.8
2.9
25 1.9
0.3
0.9
Number of visits
4.1
3.1
20 6.4
3.1
4.1
5.9
15 6.2
0.4
3.5
7.6
0.1
10 8.3
9
1.1
0.9
5 0.3
6.2
7.9
1
0 2.3
4.2
3.2
3.1
5.5
0.7
0.9
3.1
1.7
1.1
1
2.1
1.9
3.1
0.9
1.1
3.7
1.9
Visit Duration in Minutes
8. Another thing to look for is a valley. As we mentioned
before, histograms normally follow a standard distribution
Visit
Duration
1.5
Bin
0
curve which means there’s a gradual climb to the peak and a
1.8 1
5.2 2
4.4 3
6.1 4
2.1 5
0.3 6
1.3 7
1.1 8
gradual slope to the end. If the histogram has a dip, like in
6.4 9
3.8 10
2.7
2.4
2.6
3.1
1.3
the 2-3 minute bin below, that might be an indication that
1.2
1.4
1.5
0.9
5.9
4.9
9.1
2.1
something is up and requires further investigation. Your job
1
1.6
0.2
0.3
4.5
4.9
3.8
1.7
is now to find the cause of the dip.
2.1
0.8
0.1
3.2
0.7
1.1
4
7.6
1.4
1.2
5.2
3.4
3.2
Website Visit Duration Histogram
4.1
1.5
8.9
3.6
4.1
2.4
0.4
1.7
3.5
25 2.4
2.2
2.8
Number of visits
2.9
20 1.9
0.3
0.9
4.1
15
3.1
6.4
3.1
4.1
5.9
10 6.2
0.4
3.5
7.6
5 0.1
8.3
9
1.1
0 0.9
0.3
6.2
7.9
1
2.3
4.2
3.2
3.1
5.5
0.7
0.9
3.1
1.7
1.1
1
2.1
1.9
3.1
0.9
1.1
Visit Duration in Minutes
3.7
1.9
9. CRITICAL THINKING: What might account for that
unusual dip in the website duration histogram?
What story might the data be telling you?
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