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.

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________   Date: ____________

1.Easy
testdisease presentdisease absenttotalpositive36370406abnegative14750764cdtotal5011201170

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 negative predictive value NPV as a percentage. Round to one decimal place.

a = 36b = 370c = 14d = 750
NPV = %
2.Easy
testdisease presentdisease absenttotalpositive11872190abnegative7217381810cdtotal19018102000

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 prevalence in the study p as a percentage. Round to one decimal place.

a = 118b = 72c = 72d = 1738
p = %
3.Medium
testdisease presentdisease absenttotalpositive182112294abnegative4814881536cdtotal23016001830

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 likelihood ratio LR+. Round to two decimal places.

a = 182b = 112c = 48d = 1488
LR+ =
4.Medium
eventno eventtotaltreatment99491590abcontrol170540710cd

Practice exercise (made-up values, not clinical guidance). In a randomised trial, 590 patients received a new treatment and 710 received the control treatment. The table shows how many in each group had the outcome (an unwanted event such as a stroke). Find the number needed to treat NNT to prevent one event. Round up to a whole number of patients.

treatment: 99/590control: 170/710
NNT =
5.Hard
pre-test10%post-test?p′LR+

Practice exercise (made-up values, not clinical guidance). A patient has a pre-test probability of 10% for a disease. A test with sensitivity 87% and specificity 90% comes back positive. Find the post-test probability p′ of the disease as a percentage. Round to one decimal place.

pre-test 10%Se = 87%Sp = 90%positive
p′ = %
6.Hard
pre-test5%post-test?p′LR+

Practice exercise (made-up values, not clinical guidance). A patient has a pre-test probability of 5% for a disease. A test with sensitivity 89% and specificity 82% comes back positive. Find the post-test probability p′ of the disease as a percentage. Round to one decimal place.

pre-test 5%Se = 89%Sp = 82%positive
p′ = %

Answer key

  1. 1. NPV = 98.2 %
  2. 2. p = 9.5 %
  3. 3. LR+ = 11.3
  4. 4. NNT = 14
  5. 5. p′ = 49.2 %
  6. 6. p′ = 20.6 %

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