EBDM Lecture 10: Statistical Analysis II

What is used to establish the strength of the relationship between two continuous variables?

Correlation coefficient

What is the range of Correlation coefficient?

-1 to 1

Is there correlation if the Correlation coefficient is between -0.1 to 0.1?

No

If you are testing group differences and the outcome is discrete, what test would you perform?

Chi-square Test

If you are testing group differences and the outcome is continuous with two levels of variables, what test would you perform?

t-test

If you are testing group differences and the outcome is continuous with three or more levels of variables, what test would you perform?

ANOVA

If you are not testing group differences and both variables are continuous, what test would you perform?

Correlation Coefficient

Are parameters used for the population or sample?

Population

Are statistics used for the population or sample?

Sample

Do parameters use Greek or Roman letters?

Greek

Do statistics use Greek or Roman letters?

Roman

What are the two approaches of statistical inference?

1. Estimating population parameters

2. Testing research hypothesis

What is used to describe the population?

Statistical analysis

What is used to estimate the population parameters?

Statistical inference

What is used to reflect the range of values that might have resulted if study were repeated multiple times, with different samples?

95% Confidence Intervals

What test is used to screen for diseases?

Diagnostic tests

Which statistics are used to judge the value of screening tests?

1. False positives and false negatives

2. Sensitivity and specificity

3. Positive and negative predictive values

What is the probability that screening test is accurate when disease is truly present?

Sensitivity

What is the probability that screening test is accurate when disease is truly absent?

Specificity

What is the probability that disease is truly present when screening test is positive?

Positive Predictive Value

What is the probability that disease is truly present when screening test is negative?

Negative Predictive Value

What is the criteria for establishing causation developed by Sir Austin Bradford Hill?

Bradford Hill's Criteria for Causation

How many categories are used to establish causation between exposure and causation?

Nine

What represents magnitude of association/relationship between exposure and outcome?

Strength of association

What does a strong association mean for causation?

Implies causation

What does a high level of consistency reflect?

Stronger likelihood of association/relationship between exposure and outcome

What is the purest form of causation?

Specificity

What is specificity most applicable to?

Infectious disease

Which Bradford Hill's criteria is always required?

Temporality

In terms of temporality, what does causation absolutely require?

Exposure must precede outcome

What relationship does the biological gradient refer to?

Expression of outcome is dependent on expression of exposure

What can the level of exposure reflect?

1. Intensity of exposure

2. Duration of exposure

What does biological plausibility require?

Association must be supported by current understanding

Do contradictions to current understandings always imply lack of causation?

No

What is the term that requires that the casual association is compatible with existing theory?

Coherence

What does reversibility state?

Associations are affected by experiments

When is reversibility easier to establish?

Single agent is involved

What is the method basing interpretation of new associations on existing associations?

Reasoning by analogy