Real-Life Math -- Solution
You're investigating how effective your lab's testing
procedures have been for the month. To examine your testing procedures, you
compare this month's results with the results you normally get.
Start
by calculating what percentage of the total sample you had to test for foreign
or abnormal antibodies. You need to figure out the total number of tests you
performed during the month, or count period.
In January, there are
31 days. If you did 30 samples per day, multiply those numbers to come up
with the total number of tests you performed during that period.
31
x 30 = 930
Of those tests, 58 showed signs of abnormality. You
need to compare that number to the number of abnormal tests that you normally
perform during a month to see if your testing is up to your usual standards.
If the number you did this month is too much above or below your usual amount,
then your testing has been inaccurate.
Your guidelines from previous
months show that no more than 7 percent of the total blood should be abnormal.
Take the number of samples you found with foreign antibodies and divide that
by the total number of samples to find the percentage.
58 / 930
x 100 = 6 percent
Since 6 percent is below the 7 percent average,
your testing was pretty accurate.
Next you have to see how careful
your testing has been.
Of the total blood samples, 25 had to be reinvestigated
because of a faulty sample. Your guidelines show that no more than 1 percent
of the total cases should have to be re-tested.
25 / 930 x 100
= 3 percent
Three percent is well above the 1 percent average.
It looks as if you need to review your sampling procedures.
Finally
you have to evaluate the direct antigolbulin test, or DAT test. If you get
too many positive results then you probably have too sensitive a test. Remember,
53 of the abnormal cases tested negative for DAT, while 5 tested positive.
Remember that 58 of the samples showed abnormal antibodies.
5 /
58 x 100 = 9 percent
Your guidelines specify that no more than
17 percent of abnormal samples should test positive for DAT. Since only 9
percent tested positive, your DAT test seems to have been pretty effective.
The
only problem you need to report is re-testing. It looks like your lab technicians
need to be a bit more careful when they take samples!
You need solid
mathematics skills as a lab tech.
"Advanced level math
and science courses are prerequisites," agrees Alison Toupitch of the Canadian
Society for Medical Laboratory Science. Students should check the requirements
with the school of their choice.