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Flashcards in Collecting the evidence Deck (20)
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1
Q

Constructing a question - PICO

A

Patient

Intervention Comparison Outcome

2
Q

‘Anatomy’ of a good question

A
  1. Define precisely whom the question is about (how would I describe a similar group of patients)
  2. Define which option you are considering (eg drug treatment) and possible comparison (eg placebo or standard therapy)
  3. Define the desired (or undesired) outcome (eg reduced mortality, better quality of life)
3
Q

• Systematic Reviews/ Meta-analyses

A

– Secondary sources of information vetted by independent

researchers and clinicians (Cochrane Collaboration)

4
Q

• ClinicalPracticeGuidelines

A

– Reviews covering large disease groups and treatment

strategies (NICE guidelines, SIGN Guidelines)

5
Q

• Original article containing primary research data

A

– eg randomised-controlled trial (RCT)

6
Q

When trying to answer a clinical question

A
1. Start with
– Cochrane Reviews
– NICE and SIGN Guidelines
2. Then use
– MedLine (Ovid, PubMed)
7
Q

Interpreting the evidence

A
  • How are clinical studies designed
  • Different types of data
  • Hypothesis testing
  • P value and statistical significance
  • Type I and Type II errors
  • Confidence intervals
  • Number needed to treat(NNT)
  • Odds ratio
  • Forest plots
8
Q

Hypothesis construction

A

– Null hypothesis– two sets of data are from the same population and not different

– Alternative hypothesis– two sets of data are from different populations and are different

9
Q

quantitive discrete

A

can only have certain numerical

values (number of children)

10
Q

quantitive continuous

A

do not have discrete steps (height and weight)

11
Q

Nominal (unordered categories)

A

• Male/female, green/blue/ eyes, alive or dead

12
Q

Ordinal (ordered categories)

A

• Objective – heavy, moderate or light drinkers (based on the number of units of alcohol drunk per week), grade of breast cancer

13
Q

questionnaires

A

• Subjective

14
Q

Hypothesis testing

A

– Assume the null hypothesis – two sets of data are from the same population and not different
– Determine the probability that the null hypothesis is correct – P value

15
Q

p value

A

if this is one it means the null hypothesis is true

16
Q

P < 0.05

A
  • An arbitrary cut-off of 0.05 or 5% (1 chance in 20) has been chosen to indicate that the null hypothesis can be reasonably rejected
  • If P < 0.05 then there is a statistically significant difference
17
Q

Type I error

A

rejecting the null hypothesis when it is true (false positive) - concluding there is an effect when there isn’t (P is small)

18
Q

Type II error

A

not rejecting the null hypothesis when it is false (false negative) - concluding there is no effect when there is (P is large)

19
Q

Power

A

• The power of a test is its ability to reject the null hypothesis when it is false
– the capacity to detect an effect if one is present

20
Q

power questions

A

– Was the sample size large enough? – Variation small enough?