CPH Exam UPDATED ACTUAL
Questions and CORRECT Answers
Attributable risk - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - 95% confident that the true value of a
variable is contained within the interval.
-used to account for sampling variability
-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 - CORRECT ANSWER - 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 - CORRECT ANSWER - temporality: cause precedes effect
Specificity: important in assessing the possibility of biases.
Consistency: several studies showing similar results. homogeneity statistically.
Confounders - CORRECT ANSWER - -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
-not an intermediate variable on causal pathway
Controlling for confounders - CORRECT ANSWER - 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 - CORRECT ANSWER - QA: ensure quality before
data collection
QC: monitor and maintain quality during study
reliability vs. validity - CORRECT ANSWER - R: precision, reproducibility
V: accuracy, absence of bias
systematic error - CORRECT ANSWER - (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 - CORRECT ANSWER - (lack of precision) occurs, but increasing sample
size helps.
,RCT studies - CORRECT ANSWER - 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 - CORRECT ANSWER - community-wide basis or
groupwide
Case-Crossover RCT design - CORRECT ANSWER - -cases serve as their own control
-exposure has transient effect
Cross Sectional Studies - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - individual matching: case and control
matched individually
frequency matching: a group of controls
Minimum Euclidean Distance measure: match to closest person.
Cohort Studies - CORRECT ANSWER - 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.
, Concurrent/longitudinal cohort studies - CORRECT ANSWER - starts now (with a
baseline exam) and goes into future. expensive and time intensive.
non-concurrent/retrospective cohort studies - CORRECT ANSWER - assembled in past
based on existing records. faster and quicker, but records can be limited or biased. follow up can
be hard.
Prevalence of disease - CORRECT ANSWER - measure of the burden of disease in a
community (new and existing cases). the number of events in a given population at a designated
time.
-obscures causal relationships
point prevalence - CORRECT ANSWER - -proportion of pop that is diseased during a
single point of time.
-at a specific point in time
number of cases at a particular moment/
number in population at that moment
period prevalence - CORRECT ANSWER - -proportion of pop that is diseased during a
specified duration of time.
-during a specific period of time
number of cases during a specified time period/
number in population at midpoint of period
incidence of disease - CORRECT ANSWER - measure of risk (new cases)
the rate at which people without a disease develop the disease during a specific period of time.
#of new cases over a period of time/
population @ risk of the disease in that time
Questions and CORRECT Answers
Attributable risk - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - 95% confident that the true value of a
variable is contained within the interval.
-used to account for sampling variability
-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 - CORRECT ANSWER - 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 - CORRECT ANSWER - temporality: cause precedes effect
Specificity: important in assessing the possibility of biases.
Consistency: several studies showing similar results. homogeneity statistically.
Confounders - CORRECT ANSWER - -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
-not an intermediate variable on causal pathway
Controlling for confounders - CORRECT ANSWER - 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 - CORRECT ANSWER - QA: ensure quality before
data collection
QC: monitor and maintain quality during study
reliability vs. validity - CORRECT ANSWER - R: precision, reproducibility
V: accuracy, absence of bias
systematic error - CORRECT ANSWER - (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 - CORRECT ANSWER - (lack of precision) occurs, but increasing sample
size helps.
,RCT studies - CORRECT ANSWER - 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 - CORRECT ANSWER - community-wide basis or
groupwide
Case-Crossover RCT design - CORRECT ANSWER - -cases serve as their own control
-exposure has transient effect
Cross Sectional Studies - CORRECT ANSWER - 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 - CORRECT ANSWER - 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 - CORRECT ANSWER - individual matching: case and control
matched individually
frequency matching: a group of controls
Minimum Euclidean Distance measure: match to closest person.
Cohort Studies - CORRECT ANSWER - 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.
, Concurrent/longitudinal cohort studies - CORRECT ANSWER - starts now (with a
baseline exam) and goes into future. expensive and time intensive.
non-concurrent/retrospective cohort studies - CORRECT ANSWER - assembled in past
based on existing records. faster and quicker, but records can be limited or biased. follow up can
be hard.
Prevalence of disease - CORRECT ANSWER - measure of the burden of disease in a
community (new and existing cases). the number of events in a given population at a designated
time.
-obscures causal relationships
point prevalence - CORRECT ANSWER - -proportion of pop that is diseased during a
single point of time.
-at a specific point in time
number of cases at a particular moment/
number in population at that moment
period prevalence - CORRECT ANSWER - -proportion of pop that is diseased during a
specified duration of time.
-during a specific period of time
number of cases during a specified time period/
number in population at midpoint of period
incidence of disease - CORRECT ANSWER - measure of risk (new cases)
the rate at which people without a disease develop the disease during a specific period of time.
#of new cases over a period of time/
population @ risk of the disease in that time
