CPH EXAM Questions and Answers
100% Pass
Attributable risk - ✔✔Rate of disease in exposed individuals that can be attributed to
the exposure. Or the proportion of all cases that can be attributed to a particular
exposure.
Adjusted rate - ✔✔Effects of differences in composition of pops being compared have
been minimized by statistical methods.
ex: regression analysis and strandardization
-often used on rates or relative risks
Ecological Fallacy - ✔✔Bias that may occur because an association observed between
variables or an aggregate level does not represent the association that exists at an
individual level
Confidence Interval - ✔✔95% confident that the true value of a variable is contained
within the interval.
-used to account for sampling variability
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,-it is a point estimate +_ margin of error, where the point estimate is the best estimate of
teh unknown parameter and the margin of error is the product of the confidence level
and the standard error.
if a 95% CI for the differences in mean does not include 0 (the null value) then there is
eveidence of a statistically significant difference at sigma=0.05
Clinical Trial Phases - ✔✔1. Safety and Pharmacologic profiles
2. pilot efficacy studies
3. extensive clinical trials
4. after the FDA approves, look at specific effects to establish incidence of adverse
reactions, etc. longterm use effects.
interpretation of studies - ✔✔temporality: cause precedes effect
Specificity: important in assessing the possibility of biases.
Consistency: several studies showing similar results. homogeneity statistically.
Confounders - ✔✔-non-causal association between exposure and outcome as a result of
a third variable.
-distortion of effect by other factors
-must be related to exposure AND outcome
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,-not an intermediate variable on causal pathway
Controlling for confounders - ✔✔before data collection: random collection, individual
matching, frequency matching
After data collection: direct adjustment, indirect adjustment, mantel-haenszel,
regression techniques
Quality Assurance vs. Quality Control - ✔✔QA: ensure quality before data collection
QC: monitor and maintain quality during study
reliability vs. validity - ✔✔R: precision, reproducibility
V: accuracy, absence of bias
systematic error - ✔✔(lack of validity) if there's a difference between what is actually
being estimated and what is intended to be measured. Increasing sample size doesn't
help.
Random Error - ✔✔(lack of precision) occurs, but increasing sample size helps.
RCT studies - ✔✔Tests efficacy or effectiveness of healthcare services. random
allocation of participants to different treatments. Includes blinding, placebo. gold
standard for evidence.
Community Intervention/cluster RCT - ✔✔community-wide basis or groupwide
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, Case-Crossover RCT design - ✔✔-cases serve as their own control
-exposure has transient effect
Cross Sectional Studies - ✔✔SNAPSHOT! at a single point in time. tells the prevalence
and association. causation cannot be implied. a study that examines the relationship
between diseases and other variables as they exist in a defined population at one
particular time.
Matching - ✔✔used to make cases and controls as similar as possible to avoid
confounding. ex: race, gender, age. +Maybe the only way to control confounding.
increases statistical power, straightforward. -requires use of special analytical
techniques, residual confounding can occur if you match continuous variables by
category.
types of matching - ✔✔individual matching: case and control matched individually
frequency matching: a group of controls
Minimum Euclidean Distance measure: match to closest person.
Cohort Studies - ✔✔RISK RATIO, RELATIVE RISK, INCIDENCE RATE, RATE RATIO
-rare exposures
-group of subjects who shared experiences during a particular time. Determines if
incidence is related to exposure.
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100% Pass
Attributable risk - ✔✔Rate of disease in exposed individuals that can be attributed to
the exposure. Or the proportion of all cases that can be attributed to a particular
exposure.
Adjusted rate - ✔✔Effects of differences in composition of pops being compared have
been minimized by statistical methods.
ex: regression analysis and strandardization
-often used on rates or relative risks
Ecological Fallacy - ✔✔Bias that may occur because an association observed between
variables or an aggregate level does not represent the association that exists at an
individual level
Confidence Interval - ✔✔95% confident that the true value of a variable is contained
within the interval.
-used to account for sampling variability
Disclaimer: Original Content, No Copyright Infringement, All Rights Reserved © 2025 1
,-it is a point estimate +_ margin of error, where the point estimate is the best estimate of
teh unknown parameter and the margin of error is the product of the confidence level
and the standard error.
if a 95% CI for the differences in mean does not include 0 (the null value) then there is
eveidence of a statistically significant difference at sigma=0.05
Clinical Trial Phases - ✔✔1. Safety and Pharmacologic profiles
2. pilot efficacy studies
3. extensive clinical trials
4. after the FDA approves, look at specific effects to establish incidence of adverse
reactions, etc. longterm use effects.
interpretation of studies - ✔✔temporality: cause precedes effect
Specificity: important in assessing the possibility of biases.
Consistency: several studies showing similar results. homogeneity statistically.
Confounders - ✔✔-non-causal association between exposure and outcome as a result of
a third variable.
-distortion of effect by other factors
-must be related to exposure AND outcome
Disclaimer: Original Content, No Copyright Infringement, All Rights Reserved © 2025 2
,-not an intermediate variable on causal pathway
Controlling for confounders - ✔✔before data collection: random collection, individual
matching, frequency matching
After data collection: direct adjustment, indirect adjustment, mantel-haenszel,
regression techniques
Quality Assurance vs. Quality Control - ✔✔QA: ensure quality before data collection
QC: monitor and maintain quality during study
reliability vs. validity - ✔✔R: precision, reproducibility
V: accuracy, absence of bias
systematic error - ✔✔(lack of validity) if there's a difference between what is actually
being estimated and what is intended to be measured. Increasing sample size doesn't
help.
Random Error - ✔✔(lack of precision) occurs, but increasing sample size helps.
RCT studies - ✔✔Tests efficacy or effectiveness of healthcare services. random
allocation of participants to different treatments. Includes blinding, placebo. gold
standard for evidence.
Community Intervention/cluster RCT - ✔✔community-wide basis or groupwide
Disclaimer: Original Content, No Copyright Infringement, All Rights Reserved © 2025 3
, Case-Crossover RCT design - ✔✔-cases serve as their own control
-exposure has transient effect
Cross Sectional Studies - ✔✔SNAPSHOT! at a single point in time. tells the prevalence
and association. causation cannot be implied. a study that examines the relationship
between diseases and other variables as they exist in a defined population at one
particular time.
Matching - ✔✔used to make cases and controls as similar as possible to avoid
confounding. ex: race, gender, age. +Maybe the only way to control confounding.
increases statistical power, straightforward. -requires use of special analytical
techniques, residual confounding can occur if you match continuous variables by
category.
types of matching - ✔✔individual matching: case and control matched individually
frequency matching: a group of controls
Minimum Euclidean Distance measure: match to closest person.
Cohort Studies - ✔✔RISK RATIO, RELATIVE RISK, INCIDENCE RATE, RATE RATIO
-rare exposures
-group of subjects who shared experiences during a particular time. Determines if
incidence is related to exposure.
Disclaimer: Original Content, No Copyright Infringement, All Rights Reserved © 2025 4
