Frequency Plot - Medical Test

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G

I am working on an assignment where we are given a bunch
of data points representing medical tests taken to
determine whether a person has a given disease. We have
200 test results (measuring some number from 1-50 which,
at a certain cutoff value, indicates the disease is
likely present): 100 for people who actually have the
disease, and 100 for those who don't. Our mission is to
plot the data in such a way as to evaluate the
sensitivity and specificity of the test (accuracy, best
cutoff point, etc.).

What is the best way to plot this using Excel?

G
 
G said:
I am working on an assignment where we are given a bunch
of data points representing medical tests taken to
determine whether a person has a given disease. We have
200 test results (measuring some number from 1-50 which,
at a certain cutoff value, indicates the disease is
likely present): 100 for people who actually have the
disease, and 100 for those who don't. Our mission is to
plot the data in such a way as to evaluate the
sensitivity and specificity of the test (accuracy, best
cutoff point, etc.).

What is the best way to plot this using Excel?
Click to expand...

How about two separate histograms or column charts? One histogram
represents those that have the disease, the other represents those that
don't have the disease. The x-axis would have the test result (1-50), while
the y-axis would have the number of people with that test result. The
FREQUENCY and HISTOGRAM functions in Excel would be helpful.

Hopefully the two histograms are almost entirely separate, and the desired
cutoff point will be obvious. The overlap of the histograms should give
some indication of the "sensitivity and specificity" of the test, although
you'll need a statistician to put a number on that quantity.

Dave "not a statistician"
dvt at psu dot edu
 
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