American Board of Surgery Qualifying
Exam (ABS QE) fully solved
Effect modification - correct answer ✔✔The change of one factor alters the outcome involved.
Using a factor, i.e. age, to modify the effect of a putative causal factor under study.
Mode - correct answer ✔✔The number that occurs most often in a set of data
Median - correct answer ✔✔the middle score in a distribution; half the scores are above it and
half are below it
Mean - correct answer ✔✔the arithmetic average of a distribution, obtained by adding the
scores and then dividing by the number of scores
Spread - correct answer ✔✔Measured by standard deviation, variance and standard error.
Standard error depends on sample size
Continuous Data - correct answer ✔✔"Real" number, can be normal continuous data or skewed
continuous data
Ordinal Data - correct answer ✔✔Categories, but represent an order, ex. young, middle aged,
old, and pain scales
Nominal Data - correct answer ✔✔Categories, but do not have an order, ex. pancreas, liver,
kidney, ABO type
,Type I Error - correct answer ✔✔rejecting a true null hypothesis, i.e. alpha error, example is
where you think there is an difference where there is not one.
Type II Error - correct answer ✔✔accepting a false null hypothesis, i.e. beta error, example is
where you think there is no difference but one exists
case series study - correct answer ✔✔Study in which information about individual patients who
share a disease in common is gathered over time. A type of observational study.
Case Report Study - correct answer ✔✔Type of descriptive research in which only one
individual is studied in depth, often retrospectively. A type of observational study.
cohort study - correct answer ✔✔A study that starts with outcomes, uses odds ratio, a type of
observational study, i.e. risk factors to develop cancer
randomized controlled trial - correct answer ✔✔An experimental study in which researchers
randomly assign individuals to either an experimental or a control group and expose the
experimental group to the manipulated variable of interest.
systematic review - correct answer ✔✔A rigorous synthesis of research findings on a particular
research question, using systematic sampling and data collection procedures and a formal
protocol. A qualitative pooled study.
meta-analytic study - correct answer ✔✔Combined results from numerous studies to assess the
effect of common variables. A quantitative pooled study.
Sensitivity - correct answer ✔✔Sensitivity = TP / (TP + FN), positive in disease
Specificity - correct answer ✔✔Specificity = TN / (TN + FP), negative in health
,Positive Predictive Value (PPV) - correct answer ✔✔TP/(TP+FP), of those with a + test, what %
have the disease?
Negative Predictive Value (NPV) - correct answer ✔✔TN / (TN + FN)
t-test - correct answer ✔✔Normal, continuous data, 2 groups
ANOVA - correct answer ✔✔Normal, continuous data, more than 2 groups
Mann-Whitney U-test/Wilcoxon rank-sum test - correct answer ✔✔Skewed, continuous or
ordinal data, 2 groups
Friedman's ANOVA - correct answer ✔✔Ordinal data, more than 2 groups
Chi-square test - correct answer ✔✔Nominal, un-ordered categories
Fisher's exact test - correct answer ✔✔Nominal, un-ordered categories, less than <5 in a group
or box
selection bias - correct answer ✔✔A polling error in which the sample is not representative of
the population being studied, so that some opinions are over- or underrepresented
non-response bias - correct answer ✔✔Bias introduced into survey results because individuals
refuse to participate.
, treatment selection bias - correct answer ✔✔A misleading comparison between treatment and
control groups because of how people were selected into groups, usually when not based on
random assignment.
Misclassification Bias - correct answer ✔✔A type of bias that occurs when an individual is
classified into the wrong category (ex. classifying an individual as a case when in actuality
he/she is a control and vise versa).
recall bias - correct answer ✔✔Knowledge of presence of disorder alters recall by subjects
information bias - correct answer ✔✔A prejudice in the data that results when either the
respondent or the interviewer has an agenda and is not presenting impartial questions or
responding with truly honest responses, respectively
Ascertainment bias - correct answer ✔✔Bias that occurs due to differences in assessing or
analyzing outcomes by the researcher due to awareness of which participants received the
active versus control interventions.
Follow-up bias - correct answer ✔✔reason for lack of follow up relates to exposure and differs
between groups
social desirability bias - correct answer ✔✔A tendency to give socially approved answers to
questions about oneself.
lead time bias - correct answer ✔✔Bias introduced when screening detects a disease earlier
and thus lengthens the time from diagnosis to death.
Confounding bias - correct answer ✔✔Occurs when factor is related to both exposure and
outcome, but is not the the causal pathway; factor distorts or confuses effect of the exposure
on outcome
Exam (ABS QE) fully solved
Effect modification - correct answer ✔✔The change of one factor alters the outcome involved.
Using a factor, i.e. age, to modify the effect of a putative causal factor under study.
Mode - correct answer ✔✔The number that occurs most often in a set of data
Median - correct answer ✔✔the middle score in a distribution; half the scores are above it and
half are below it
Mean - correct answer ✔✔the arithmetic average of a distribution, obtained by adding the
scores and then dividing by the number of scores
Spread - correct answer ✔✔Measured by standard deviation, variance and standard error.
Standard error depends on sample size
Continuous Data - correct answer ✔✔"Real" number, can be normal continuous data or skewed
continuous data
Ordinal Data - correct answer ✔✔Categories, but represent an order, ex. young, middle aged,
old, and pain scales
Nominal Data - correct answer ✔✔Categories, but do not have an order, ex. pancreas, liver,
kidney, ABO type
,Type I Error - correct answer ✔✔rejecting a true null hypothesis, i.e. alpha error, example is
where you think there is an difference where there is not one.
Type II Error - correct answer ✔✔accepting a false null hypothesis, i.e. beta error, example is
where you think there is no difference but one exists
case series study - correct answer ✔✔Study in which information about individual patients who
share a disease in common is gathered over time. A type of observational study.
Case Report Study - correct answer ✔✔Type of descriptive research in which only one
individual is studied in depth, often retrospectively. A type of observational study.
cohort study - correct answer ✔✔A study that starts with outcomes, uses odds ratio, a type of
observational study, i.e. risk factors to develop cancer
randomized controlled trial - correct answer ✔✔An experimental study in which researchers
randomly assign individuals to either an experimental or a control group and expose the
experimental group to the manipulated variable of interest.
systematic review - correct answer ✔✔A rigorous synthesis of research findings on a particular
research question, using systematic sampling and data collection procedures and a formal
protocol. A qualitative pooled study.
meta-analytic study - correct answer ✔✔Combined results from numerous studies to assess the
effect of common variables. A quantitative pooled study.
Sensitivity - correct answer ✔✔Sensitivity = TP / (TP + FN), positive in disease
Specificity - correct answer ✔✔Specificity = TN / (TN + FP), negative in health
,Positive Predictive Value (PPV) - correct answer ✔✔TP/(TP+FP), of those with a + test, what %
have the disease?
Negative Predictive Value (NPV) - correct answer ✔✔TN / (TN + FN)
t-test - correct answer ✔✔Normal, continuous data, 2 groups
ANOVA - correct answer ✔✔Normal, continuous data, more than 2 groups
Mann-Whitney U-test/Wilcoxon rank-sum test - correct answer ✔✔Skewed, continuous or
ordinal data, 2 groups
Friedman's ANOVA - correct answer ✔✔Ordinal data, more than 2 groups
Chi-square test - correct answer ✔✔Nominal, un-ordered categories
Fisher's exact test - correct answer ✔✔Nominal, un-ordered categories, less than <5 in a group
or box
selection bias - correct answer ✔✔A polling error in which the sample is not representative of
the population being studied, so that some opinions are over- or underrepresented
non-response bias - correct answer ✔✔Bias introduced into survey results because individuals
refuse to participate.
, treatment selection bias - correct answer ✔✔A misleading comparison between treatment and
control groups because of how people were selected into groups, usually when not based on
random assignment.
Misclassification Bias - correct answer ✔✔A type of bias that occurs when an individual is
classified into the wrong category (ex. classifying an individual as a case when in actuality
he/she is a control and vise versa).
recall bias - correct answer ✔✔Knowledge of presence of disorder alters recall by subjects
information bias - correct answer ✔✔A prejudice in the data that results when either the
respondent or the interviewer has an agenda and is not presenting impartial questions or
responding with truly honest responses, respectively
Ascertainment bias - correct answer ✔✔Bias that occurs due to differences in assessing or
analyzing outcomes by the researcher due to awareness of which participants received the
active versus control interventions.
Follow-up bias - correct answer ✔✔reason for lack of follow up relates to exposure and differs
between groups
social desirability bias - correct answer ✔✔A tendency to give socially approved answers to
questions about oneself.
lead time bias - correct answer ✔✔Bias introduced when screening detects a disease earlier
and thus lengthens the time from diagnosis to death.
Confounding bias - correct answer ✔✔Occurs when factor is related to both exposure and
outcome, but is not the the causal pathway; factor distorts or confuses effect of the exposure
on outcome
