Statistics Case 10: ANM 150

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Questions and Answers

What is the definition of prevalence in statistics?

The number of new cases of a disorder within a specific time period

The likelihood of an outcome in a control group

The difference in group means between treatment and control groups

The total number of cases suffering from a disorder (correct)

What is the primary purpose of hypothesis testing in statistics?

To calculate the p-value of a statistical test

To determine the confidence interval of a statistical test

To decide whether the findings of an investigation reflect chance or real effect (correct)

To determine the difference in group means between treatment and control groups

What does a p-value of 0.03 indicate in a statistical test?

The result is statistically significant (correct)

The result is not statistically significant

The confidence interval is 95%

The sample size is too small

What does it mean if the 95% confidence intervals of two groups do not overlap?

The result is statistically significant Signup and view all the answers

What is the definition of incidence in statistics?

The number of new cases of a disorder within a specific time period Signup and view all the answers

What is the concept of power in statistical significance?

The ability to detect a difference due to the sample size Signup and view all the answers

What is the Relative Risk (RR) of a bad outcome in the intervention group if the event rate is 12% in the intervention group and 20% in the control group?

0.6 Signup and view all the answers

What is the Absolute Risk Reduction (ARR) if the risk of a bad outcome is reduced from 20% to 12%?

8% Signup and view all the answers

What is the Relative Risk Reduction (RRR) if the Relative Risk (RR) is 0.6?

40% Signup and view all the answers

What happens when outcomes occur infrequently?

You can see a large difference between the Absolute Risk Reduction (ARR) and the Relative Risk Reduction (RRR) Signup and view all the answers

What is the primary purpose of a surrogate outcome?

To predict the effect on a true outcome Signup and view all the answers

What is the interpretation of an odds ratio (OR) equal to 1?

Exposure does not affect the likelihood of the outcome Signup and view all the answers

What is the primary limitation of statistical significance?

It is heavily dependent on sample size Signup and view all the answers

What is the difference between clinical significance and statistical significance?

Clinical significance is related to the extent of change, while statistical significance is related to sample size Signup and view all the answers

What is the purpose of validating a surrogate outcome?

To show it predicts the true outcome Signup and view all the answers

Study Notes

Statistics Case 10: ANM 150

Objectives

Define terms: sample, population, incidence, prevalence, and more
Describe the process of hypothesis testing and assessing statistical significance
Interpret Relative and Absolute Risk, Odds ratio, number needed to treat/harm, and power
Differentiate between clinical and surrogate outcomes and their respective strengths

Terminology

Population: the entire group of people being studied
Sample: a subset of the population

Prevalence and Incidence

Prevalence: the total number of cases suffering from a disorder
Incidence: the number of new cases suffering from a disorder
Example: 26,630 people in Ontario are HIV positive (prevalence), and 1,620 people were newly infected with HIV in Ontario (incidence)

Hypothesis Testing

The process of deciding whether the findings of an investigation reflect chance or real effect
Statistical significance: determining whether the difference between groups is real or due to chance

Statistical Significance: P-Value and Confidence Interval

P-value: the probability that the difference is due to chance
P-value < 0.05: significant difference (less than 5% likelihood of chance)
P-value > 0.05: not significant
95% Confidence Interval (CI): a range of values within which the true result is likely to lie

Relative Risk and Risk Reduction

Relative Risk (RR): the probability of a bad outcome in the intervention group divided by the probability of a bad outcome in the control group
RR > 1: increased risk of bad outcome with treatment
RR < 1: decreased risk of bad outcome with treatment
Relative Risk Reduction (RRR): the proportion of reduction in risk of bad outcome
Absolute Risk Reduction (ARR): the absolute difference in risk of bad outcome between treatment and control groups

Odds Ratio

Odds Ratio (OR): the relationship between an exposure and an outcome
OR = 1: exposure does not affect the likelihood of the outcome
OR > 1: exposure associated with increased likelihood of the outcome
OR < 1: exposure associated with decreased likelihood of the outcome

Outcomes

Clinical Outcomes: a clinical event (e.g., stroke, suicide, hip fracture)
Surrogate Outcomes: an indicator that can be observed sooner, at a lower cost, or less invasively (e.g., biomarkers, indicators of disease progression)

Statistical Significance vs. Clinical Significance

Statistical Significance: the difference is not due to chance (p-value < 0.05)
Clinical Significance: the intervention has a genuine, measurable effect that makes a real difference in the lives of patients

Power

The ability of a study to detect a real difference between two groups
Depends on sample size and the magnitude of the effect

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Description

This quiz covers key concepts in statistics, including terms, hypothesis testing, and interpretation of statistical measures such as risk and odds ratio. Test your understanding of population, sample, and outcome types.