USMLE Step 2 Family Med 2026
Expert Verified | Ace the Test
Positive predictive value (PPV): - 🧠 ANSWER ✔✔# of TP / total # of ppl
who tested positive for the dz
*P*ositive predictive value calculated as: - 🧠 ANSWER ✔✔T*P* / (T*P* +
F*P*)
Sensitivity: - 🧠 ANSWER ✔✔portion of dz person who have a positive test
,*diseased pt with positive test*
Highly sensitive test: - 🧠 ANSWER ✔✔used to rule out dz and have a low
FN rate, therefore *if pt has negative result* one can *rule out dz* in the pt
High sensitivity: - 🧠 ANSWER ✔✔*increases the NPV* of a test, allowing
person to *rule out a dz* if the result is negative.
Specificity: - 🧠 ANSWER ✔✔proportion of *dz free persons* appropriately
classified by the screening test as negative.
TN/ (FP + TN)
Specificity allows: - 🧠 ANSWER ✔✔person to *rule in* a dz w/ confidence
Highly specific test will reduce: - 🧠 ANSWER ✔✔FP results
Highly specific test are used to: - 🧠 ANSWER ✔✔confirm dx;
Ex: dsDNA for SLE
Test w/High specificities or probability of negative test in ppl w/o dz: - 🧠
ANSWER ✔✔reduce the false-positive rate.
,Both sensitivity and specificity of tests must be know to determine: - 🧠
ANSWER ✔✔the probability that a pt who tests positive for a dz actually
does have the dz (PPV of the test)
To determine the PPV: - 🧠 ANSWER ✔✔prevalence of dz must be known;
lower dz prevalence = lower PPV = less reliable positive test
Confounding variables: - 🧠 ANSWER ✔✔variable that can afffect the
outcome of a study, are not evenly distributed betw the study groups, and
are not part of the primary intervention
Negative predictice value: - 🧠 ANSWER ✔✔calculated as:
# of healthy pts w/ neg. test
-----------divided by --------------
# of healthy pts w/ neg test *+* # of dz pts w/ neg test.
Negative predictive value: - 🧠 ANSWER ✔✔how many of the "negative
tested" pts actually have dz
*N*egative predictive value calculated: - 🧠 ANSWER ✔✔T*N* / (T*N* +
F*N*)
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2026. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
PRIVACY STATEMENT. ALL RIGHTS RESERVED
, Case control studies: - 🧠 ANSWER ✔✔usually presented as odds ratio,
determines the likelihood of exposure to a risk factor in individuals w/ and
w/o dz
Double-blind study: - 🧠 ANSWER ✔✔eliminates observer bias
Single-blind study: - 🧠 ANSWER ✔✔only pt is blinded as to which tx he/she
is getting
Enrollment bias: - 🧠 ANSWER ✔✔pts are assigned to different study
groups in a nonrandom fashion
Lead time bias: - 🧠 ANSWER ✔✔study that measures the survival benefit
of dz screening programs;
it refers to the mistaken interpretation of data as demonstrating survival
benefit
Measurement bias: - 🧠 ANSWER ✔✔systemic error in data collection;
the process of collecting data affects the outcome.
Ex. when asked abt weekly alcohol intake, ppl tend to give answers that
are less than the true value.
Expert Verified | Ace the Test
Positive predictive value (PPV): - 🧠 ANSWER ✔✔# of TP / total # of ppl
who tested positive for the dz
*P*ositive predictive value calculated as: - 🧠 ANSWER ✔✔T*P* / (T*P* +
F*P*)
Sensitivity: - 🧠 ANSWER ✔✔portion of dz person who have a positive test
,*diseased pt with positive test*
Highly sensitive test: - 🧠 ANSWER ✔✔used to rule out dz and have a low
FN rate, therefore *if pt has negative result* one can *rule out dz* in the pt
High sensitivity: - 🧠 ANSWER ✔✔*increases the NPV* of a test, allowing
person to *rule out a dz* if the result is negative.
Specificity: - 🧠 ANSWER ✔✔proportion of *dz free persons* appropriately
classified by the screening test as negative.
TN/ (FP + TN)
Specificity allows: - 🧠 ANSWER ✔✔person to *rule in* a dz w/ confidence
Highly specific test will reduce: - 🧠 ANSWER ✔✔FP results
Highly specific test are used to: - 🧠 ANSWER ✔✔confirm dx;
Ex: dsDNA for SLE
Test w/High specificities or probability of negative test in ppl w/o dz: - 🧠
ANSWER ✔✔reduce the false-positive rate.
,Both sensitivity and specificity of tests must be know to determine: - 🧠
ANSWER ✔✔the probability that a pt who tests positive for a dz actually
does have the dz (PPV of the test)
To determine the PPV: - 🧠 ANSWER ✔✔prevalence of dz must be known;
lower dz prevalence = lower PPV = less reliable positive test
Confounding variables: - 🧠 ANSWER ✔✔variable that can afffect the
outcome of a study, are not evenly distributed betw the study groups, and
are not part of the primary intervention
Negative predictice value: - 🧠 ANSWER ✔✔calculated as:
# of healthy pts w/ neg. test
-----------divided by --------------
# of healthy pts w/ neg test *+* # of dz pts w/ neg test.
Negative predictive value: - 🧠 ANSWER ✔✔how many of the "negative
tested" pts actually have dz
*N*egative predictive value calculated: - 🧠 ANSWER ✔✔T*N* / (T*N* +
F*N*)
COPYRIGHT©PROFFKERRYMARTIN 2025/2026. YEAR PUBLISHED 2026. COMPANY REGISTRATION NUMBER: 619652435. TERMS OF USE.
PRIVACY STATEMENT. ALL RIGHTS RESERVED
, Case control studies: - 🧠 ANSWER ✔✔usually presented as odds ratio,
determines the likelihood of exposure to a risk factor in individuals w/ and
w/o dz
Double-blind study: - 🧠 ANSWER ✔✔eliminates observer bias
Single-blind study: - 🧠 ANSWER ✔✔only pt is blinded as to which tx he/she
is getting
Enrollment bias: - 🧠 ANSWER ✔✔pts are assigned to different study
groups in a nonrandom fashion
Lead time bias: - 🧠 ANSWER ✔✔study that measures the survival benefit
of dz screening programs;
it refers to the mistaken interpretation of data as demonstrating survival
benefit
Measurement bias: - 🧠 ANSWER ✔✔systemic error in data collection;
the process of collecting data affects the outcome.
Ex. when asked abt weekly alcohol intake, ppl tend to give answers that
are less than the true value.
