Intro to Evidence Based Medicine

Question 1

EBM triad domains

Answer 1

• clinical judgement
• best relevant evidence
• pt’s preferences & values

Question 2

types of empirical evidence

Answer 2

observations = data grounded in physical reality
quantitative = chemical & biological processes that involve the use of stats

Question 3

function of stats

Answer 3

1. Summarize a set of data
2. Measure the degree of association between 2 variables
3. Control potential confounding variables
4. Predict future health outcomes
5. Distinguish in sample data between genuine trends and random variability

Question 4

descriptive statistics

Answer 4

frequency & percentage for categorical variables

ex) pie charts or bar graphs of BMI category

Question 5

continuous variables

Answer 5

mean

standard deviations

Question 6

measure of effect size

Answer 6

quantifies effect of X on Y
effect can be:
-causal
-statistical relationship

Question 7

purpose of clinical research

Answer 7

investigates the causes of disease, factors that prevent disease, and treatments that restore health
-empirical investication

Question 8

categorical variables

Answer 8

BMI

Question 9

box plot

Answer 9

graphical technique which is useful for determining if the data are skewed and for detecting outliers

Question 10

whiskers in a box plot

Answer 10

drawn from each end of the box to a point

-indicates outliers by the IQR

Question 11

interquartile range

Answer 11

distance between the 75th and 25th percentiles in a box plot

Question 12

top whisker in box plot

Answer 12

1.5 IQR above the 75th percentile

Question 13

bottom whisker in box plot

Answer 13

below the 25th percentile

Question 14

mild outliers

Answer 14

more than 1.5 IQR

-represented as circles in a box plot

Question 15

extreme outliers

Answer 15

more than 3.0 IQR

-represented as asterisks in a box plot

Question 16

effect

Answer 16

refers to either a causal or a statistical relationship

Question 17

Risk Reduction Measures

Answer 17

• The more a treatment reduces risk,
• The greater will be the ARR
• The greater will be the RRR
• The smaller will be the NNT

Question 18

confounding variables

Answer 18

methods of statistical control

-referred to as Z

Question 19

statistical control

Answer 19

quantify the degree of relationship between X and Y after taking into account a third variable (Z) that is related to both

Question 20

regression analysis

Answer 20

popular method for statistically controlling confounding variables

Question 21

prognostic statistics

Answer 21

Predict future health-related outcomes

-based on various characteristics of that patient

Question 22

inferential statistics

Answer 22

Distinguish in sample data between genuine trends and random variability
-help researchers to decide whether what was found to be true of the sample
*
Is likely to be true of the population?
or
Was just due to random sampling variability (chance)?

Question 23

test statistics

Answer 23

generate 95% confidence intervals and P values

Question 24

types of inferential statistics (test statistics)

Answer 24

1. Z (generated by the Z-test)
2. t (generated by the t-test)
3. F (generated by the F-test)
4. Χ2 (generated by the chi-square test)
5. Wald (generated by the Wald test)
   * All are used to compute 95% CIs and P values.

Question 25

Evidence-based medicine is the intersection of 3 sets of considerations. One of these is Clinical Judgment. What are the other two?

Answer 25

2. Patient’s Preferences and Values

3. Best Relevant Evidence

Question 26

Identify type of statistic: The probability of recurrence of breast cancer over the next 10 years for a postmenopausal woman who does not smoke.

Answer 26

Prognostic statistic

Question 27

Identify type of statistic: The proportion in a sample of Americans who are hypertensive.

Answer 27

Descriptive statistic

Question 28

Identify type of statistic: A 95% confidence interval for the proportion of Americans in the population who are hypertensive.

Answer 28

Inferential statistic

Question 29

Identify type of statistic: The correlation between the body mass index (BMI) of anorexics and their preferred BMI.

Answer 29

Measure of effect size

Question 30

Identify type of statistic: Using regression to take into account gender in a study of the relationship between forced expiratory volume and age in a sample of children.

Answer 30

Statistical control

Question 31

the 3 conditions required to establish causality in a clinical study

Answer 31

1. Covariation
2. Correct time order
3. Absence of plausible alternative explanations

Question 32

Covariation

Answer 32

To show that one variable (X) is a cause of another (Y), researchers must first show that the 2 variables covary or are correlated
> If Y is a disease, and X is a suspected cause, then the presence of X must be shown to be associated with the presence OR the absence of Y
ex) lung CA and smoking
X (prevention) - no Y ( disease)
ex) flu vaccine and absence of flu

Question 33

how clinical researchers document associations between cause & effect

Answer 33

in terms of likelihood, tendencies or what is true on average

ex) People who smoke should be more likely to contract lung cancer.
ex) Patients who receive acupuncture should on average experience less severe headaches.

Question 34

likelihood

Answer 34

measured in terms of probability or odds

Question 35

probability

Answer 35

number of times an outcome will occur divided by the number of times the outcome could occur
* varies from 0 to 1

Question 36

Odds

Answer 36

The probability an outcome will occur divided by the probability the outcome will not occur
* vary from 0 to infinity