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 absenttotalpositive95659754abnegative1511211136cdtotal11017801890

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 accuracy Acc as a percentage. Round to one decimal place.

a = 95b = 659c = 15d = 1121
Acc = %
2.Easy
testdisease presentdisease absenttotalpositive26128154abnegative1410321046cdtotal4011601200

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 = 26b = 128c = 14d = 1032
p = %
3.Medium
eventno eventtotaltreatment123147270abcontrol319591910cd

Practice exercise (made-up values, not clinical guidance). In a randomised trial, 270 patients received a new treatment and 910 received the control treatment. The table shows how many in each group had a side effect. Find the relative risk RR of the event with treatment. Round to two decimal places.

treatment: 123/270control: 319/910
RR =
4.Medium
testdisease presentdisease absenttotalpositive131342473abnegative39558597cdtotal1709001070

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 likelihood ratio LR−. Round to two decimal places.

a = 131b = 342c = 39d = 558
LR− =
5.Hard
CER4%EER?RRR 31%

Practice exercise (made-up values, not clinical guidance). A treatment reduces the risk of an event by 31% in relative terms (RRR = 31%). In a patient group the risk without treatment (CER) is 4% over five years. Find the number needed to treat NNT for five years to prevent one event. Round up to a whole number of patients.

RRR = 31%CER = 4%
NNT =
6.Hard
testdisease presentdisease absenttotalpositive?negativetotal10 000

Practice exercise (made-up values, not clinical guidance). 10 000 people are screened with a test of sensitivity 86% and specificity 82%. The prevalence of the disease is 27%. How many positive results n₊ are expected in total?

N = 10 000p = 27%Se = 86%Sp = 82%
n₊ =

Answer key

  1. 1. Acc = 64.3 %
  2. 2. p = 3.3 %
  3. 3. RR = 1.3
  4. 4. LR− = 0.37
  5. 5. NNT = 81
  6. 6. n₊ = 3636

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