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 absenttotalpositive166529695abnegative3413611395cdtotal20018902090

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 = 166b = 529c = 34d = 1361
NPV = %
2.Easy
testdisease presentdisease absenttotalpositive179310489abnegative101660761cdtotal2809701250

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 = 179b = 310c = 101d = 660
Acc = %
3.Medium
testdisease presentdisease absenttotalpositive351159510abnegative3914311470cdtotal39015901980

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 = 351b = 159c = 39d = 1431
LR+ =
4.Medium
casescontrolsexposed2059abnot exposed110131cd

Practice exercise (made-up values, not clinical guidance). A case-control study compares 130 patients with a disease (cases) and 190 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 = 20b = 59c = 110d = 131
OR =
5.Hard
p (%)NPV (%)5%NPV = ?100

Practice exercise (made-up values, not clinical guidance). A screening test has a sensitivity of 93% and a specificity of 83%. It is used in a population where the prevalence is 5%. Find the negative predictive value NPV as a percentage. Round to one decimal place.

Se = 93%Sp = 83%p = 5%
NPV = %
6.Hard
CER38%EER?RRR 26%

Practice exercise (made-up values, not clinical guidance). A treatment reduces the risk of an event by 26% in relative terms (RRR = 26%). In a patient group the risk without treatment (CER) is 38% 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 = 26%CER = 38%
NNT =

Answer key

  1. 1. NPV = 97.6 %
  2. 2. Acc = 67.1 %
  3. 3. LR+ = 9
  4. 4. OR = 0.4
  5. 5. NPV = 99.6 %
  6. 6. NNT = 11

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