Evidence-based practice statistics worksheet with answers

Free printable Evidence-based practice statistics worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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Name: ____________________   Date: ____________

1.Easy
testdisease presentdisease absenttotalpositive104107211abnegative3614231459cdtotal14015301670

Practice exercise (made-up values, not clinical guidance). A new test was compared with the reference standard in a study (see the 2 × 2 table). Find the sensitivity Se as a percentage. Round to one decimal place.

a = 104b = 107c = 36d = 1423
Se = %
2.Easy
testdisease presentdisease absenttotalpositive183150333abnegative1079201027cdtotal29010701360

Practice exercise (made-up values, not clinical guidance). A new test was compared with the reference standard in a study (see the 2 × 2 table). Find the positive predictive value PPV as a percentage. Round to one decimal place.

a = 183b = 150c = 107d = 920
PPV = %
3.Medium
casescontrolsexposed15120abnot exposed125400cd

Practice exercise (made-up values, not clinical guidance). A case-control study compares 140 patients with a disease (cases) and 520 people without it (controls). The table shows how many in each group were exposed to a risk factor. Find the odds ratio OR for the exposure. Round to two decimal places.

a = 15b = 120c = 125d = 400
OR =
4.Medium
peopleyears1470425101new cases31

Practice exercise (made-up values, not clinical guidance). In a cohort, groups of people were followed for different lengths of time (see the table: number of people and years of follow-up for each). During follow-up, 31 new cases occurred. Find the incidence rate IR per 1000 person-years. Round to one decimal place.

470 × 4 years510 × 1 year31 new cases
IR = per 1000 person-years
5.Hard
p (%)NPV (%)15%NPV = ?100

Practice exercise (made-up values, not clinical guidance). A screening test has a sensitivity of 79% and a specificity of 80%. It is used in a population where the prevalence is 15%. Find the negative predictive value NPV as a percentage. Round to one decimal place.

Se = 79%Sp = 80%p = 15%
NPV = %
6.Hard
pre-test20%post-test?p′LR−

Practice exercise (made-up values, not clinical guidance). A patient has a pre-test probability of 20% for a disease. A test with sensitivity 85% and specificity 92% comes back negative. Find the post-test probability p′ of the disease as a percentage. Round to one decimal place.

pre-test 20%Se = 85%Sp = 92%negative
p′ = %

Answer key

  1. 1. Se = 74.3 %
  2. 2. PPV = 55 %
  3. 3. OR = 0.4
  4. 4. IR = 13 per 1000 person-years
  5. 5. NPV = 95.6 %
  6. 6. p′ = 3.9 %

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