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Semester 4 (NME) > EBM > Flashcards

Flashcards in EBM Deck (30)
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1
Q

What p value would cause one to accept the null hypothesis of a chi-squared analysis?

A

p > 0.05

2
Q

When would linear regression be used?

A

To help predict a variable from another variable

So you draw out a line chart and use one value to predict the other

3
Q

When would an un-paired t-test be used?

A

To compare the means of two unrelated populations

4
Q

When would a paired t-test be used?

A

To compare the means of two related populations (e.g. the same population before and after)

5
Q

What is a meta-analysis?

A

Combining results from different studies

6
Q

What is sensitivity?

A

Measures the proportion of +ve’s identified (e.g % of sick people identified as sick).
TRUE POSITIVE RATE

7
Q

What is specificity?

A

Measure the proportion of -ve’s identified (e.g. % of healthy people correctly identified as not sick).
TRUE NEGATIVE RATE

8
Q

The most important 3 factors when assessing a clinical trial are…

A

Validity, results and clinical relevance

9
Q

When would you use regression and what are the two types?

A

To predict dependant variable from independant
Can correct for confunding variables
Linear- when continous outcomes
Logistic- When binary outcomes

10
Q

What is the t-test used for?

A

Tests the change in mean between two groups

CONTINUOUS VARIABLE

11
Q

What is the chi-squared test used for?

A

Version of t-test to see if expected freq = anticipated frequency (testing null hypothesis)
BINARY VARIABLES ONLY

12
Q

What equation is used to calculate odds ?

A

Number of individuals without outcome

13
Q

What equation is used to calculate odds ratio?

A

odds of the outcome in another group (e.g. control)

14
Q

What is implied by an odds ratio of 1?

A

No difference between the two groups

15
Q

What is used to test the significance of odds ratio’s?

A

Chi squared
Allows us to compare proportions across two different groups.
Tells us whether the comparison is statistically significant (it gives a p value).

16
Q

What is Multiple (or multivariate) logistic regression used for?

A

Used to assess the predictive value of one or more variables on a YES/NO outcome

17
Q

You are asked: “How does smoking affect the likelihood of having pancreatitis, after accounting for (or ‘unconfounded by’ or ‘independent of’) alcohol consumption, BMI, etc.?”. What do you use to find the answer?

A

Multiple logistic regression

18
Q

What is positive predictive value?

A

Probability that the disease is present when the test is positive.

19
Q

What is negative predictive value?

A

Probability that the disease is not present when the test is negative.

20
Q

What equation is used to work out positive predictive value?

A

(true positives + false positives)

21
Q

What equation is used to work out negative predictive value?

A

(true negatives + false negatives)

22
Q

The true positive rate is also known as…..?

A

Sensitivity

23
Q

False positive rate is also known as….

A

(1- Specificity)

24
Q

What is found on the x and y axis of ROC curves?

A

x axis = (1- specificity)

y axis= Sensitivity

25
Q

What does ROC stand for?

A

Receiver Operating Characteristic

26
Q

What are ROC curves used for in a clinical context?

A

Setting test cut off points

27
Q

What does the null hypothesis usually state?

A

That the difference between the two means is 0

so intervention makes no difference

28
Q

What p value would cause you to reject the null hypothesis?

A

p less than 0.05

29
Q

What is a categorical variable?

A

Can take a fixed number of values

30
Q

What is a discrete variable?

A

Can take any of a number of values