Behavioral Science

Question 1

Odd Case

observational and retrospective

Answer 1

Compares a group of people with disease to a
group without disease.
Looks for prior exposure or risk factor.
Asks, “What happened?”

Odds ratio-ad/bc

Question 2

Relative Cohort

Answer 2

a group of people that all have something in common. no one has disease of interest

Compares a group with a given exposure or risk
factor to a group without such exposure.
Looks to see if exposure t the likelihood of
disease.
Can be prospective (asks, “Who will
develop disease?”) or retrospective (asks,
“Who developed the disease [exposed vs.
non exposed]?”).

Relative risk=a/(a+b)//c/(c+d)

Question 3

Cross sectional

prevalence study

Answer 3

Disease prevelance. Snap shot of population at a given time.

Collects data from a group of people to assess
frequency of disease (and related risk factors)
at a particular point in time.
Asks, “What is happening?”

Can show risk factor association with disease, but
does not establish causality.

Question 4

Clinical trial

Answer 4

I-is it safe (sm number of healthy pts)
II-does it work (sm # of pts with disease)
III-does it work better (comparison) large population
IV-rare or long term adverse effects

Question 5

Cross over study

Answer 5

subjects are randomly allocated to a sequence of 2 or more tx given consecutively. Pts serve as their own controls. Drawback of crossover trials is that the effects of tx 1 may carry over and alter the response of the subsequent tx. A “washout” period helps with this.

limits confounding bias

Question 6

Sensitivity

Answer 6

Used for screening test with low prevalence.
=1-FN rate
SNOUT= Sensitivity rules OUT

Question 7

Specificity

Answer 7

Used for confirmatory test after a positive screening test.
=1-FP
SPIN=specificity rules IN

Question 8

PPV

Answer 8

PPV varies directly with prevalence or pretest

probability: high pretest probability–>high PPV

Question 9

NPV

Answer 9

NPV varies inversely with prevalence or pretest

probability: high pretest probability–>low NPV

Question 10

Attributable risk

Answer 10

The difference in risk between exposed and
unexposed groups, or the proportion of
disease occurrences that are attributable to the
exposure

a/(a+b)–c/(c+d)

Question 11

Number needed to tx

Answer 11

Number of patients who need to be treated for 1
patient to benefit. Calculated as 1/absolute risk
reduction.

Question 12

Absolute risk reduction

Answer 12

c/(c+d)–a/(a+b)

Absolute reduction in risk associated with a
treatment as compared to a control

Question 13

Number needed to harm

Answer 13

Number of patients who need to be exposed
to a risk factor for 1 patient to be harmed.
Calculated as 1/attributable risk.

Question 14

Precision

Answer 14

The consistency and reproducibility of a test
(reliability).
The absence of random variation in a test.

Random error-reduces precision in a test.
Inc precision–> dec standard deviation.

Question 15

Accuracy

Answer 15

The trueness of test measurements (validity). The
absence of systematic error or bias in a test.

Systematic error-reduces accuracy in a test.

Question 16

Sampling bias

Answer 16

Subjects are not representative of the general
population; therefore, results are not
generalizable. A type of selection bias.

Question 17

Late look bias

Answer 17

Information gathered at an inappropriate
time-e.g., using a survey to study a fatal
disease (only those patients still alive will be
able to answer survey)

Question 18

Procedure bias

Answer 18

Subjects in different groups are not treated the
same-e.g., more attention is paid to treatment
group, stimulating greater adherence

Question 19

Lead time bias

Answer 19

Early detection confused with t survival; seen
with improved screening (natural history of
disease is not changed, but early detection
makes it seem as though survival Inc)

Question 20

Observer expectancy effect

Answer 20

Occurs when a researcher’s belief in the efficacy
of a treatment changes the outcome of that
treatment

Expecting results your way, lol

Question 21

Hawthorne effect

Answer 21

Occurs when the group being studied changes
its behavior owing to the knowledge of being
studied

Question 22

Mean

Answer 22

average of all values

Question 23

Median

Answer 23

falls right in the middle of all values

Question 24

mode

Answer 24

the number that occurs most frequently

Question 25

Normal distribution

Answer 25

Gaussian, also called bell-shaped.

Mean =median= mode.

Question 26

Positive skew

Answer 26

Typically, mean > median > mode.
Asymmetry with longer tail on right.
Mode is least affected by outliers in the sample.

Question 27

Negative skew

Answer 27

Typically, mean <mode.

Asymmetry with longer tail on left.

Question 28

Type 1 error (alpha)

Answer 28

Also known as false-positive error.
If p < .05, then there is less than a 5% chance
that the data will show something that is not
really there.
alpha= you saw a difference that did not exist-e.g.,
(convicting an innocent man.)

Question 29

Type 2 error (beta)

Answer 29

Also known as false-negative error.
Beta =you were blind to a difference that did
exist-e.g., (setting a guilty man free).

Question 30

Confidence Interval

Answer 30

CI =mean +/- Z(SEM)
SEM=SD/square root of the sample size
For the 95% CI, Z = 1.96. (2)
For the 99% CI, Z = 2.58. (3)

If the 95% CI for a mean difference between 2
variables includes 0, then there is no significant
difference and H0 is not rejected.
If the 95% CI for odds ratio or relative risk
includes l, H0 is not rejected.
If the CIs between 2 groups do not overlap
–>significant difference exists.
If the Cis between 2 groups overlap–>usually
no significant difference exists.

Question 31

t test

Answer 31

Checks difference between the means of 2

groups.

Question 32

ANOVA

Answer 32

Checks difference between the means of 3 or

more groups.

Question 33

Chi-squared

Answer 33

Test checks difference between 2 or more
percentages or proportions of categorical
outcomes (not mean values).

Question 34

Disease prevention

Answer 34

PDR:
Prevent (vacciations)
Detect (screen)
Reduce disability (treat)

Question 35

APGAR

Answer 35

Assessment of newborn vital signs following labor via a 10-point scale evaluated at l minute and
5 minutes. Apgar score is based on Appearance, Pulse, Grimace, Activity, and Respiration (

Question 36

Grief

Answer 36

Normal bereavement characterized by shock, denial, guilt, and somatic symptoms. Can last up to 1 year. May experience illusions.
Pathologic grief includes excessively intense grief; prolonged grief lasting > 2-6 months; or grief
that is delayed, inhibited, or denied. May experience depressive symptoms, delusions, and
hallucinations.

Question 37

REM Sleep

Answer 37

Serotonergic predominance of raphe nucleus is
key to initiating sleep.

Alcohol, benzodiazepines, and barbiturates are
associated with reduced REM and delta sleep.
Benzodiazepines are useful for night terrors and
sleepwalking.

Occurs every 90 minutes; duration inc through the night. ACh is the principal neurotransmitter in REM sleep. NE reduce REM sleep.

Findings: Inc and variable pulse and blood pressure. Extraocular movements during REM sleep due to activity of PPRF (paramedian pontine reticular formation/conjugate gaze center). Penile/clitoral tumescence.

REM sleep is like sex: Inc pulse, penile/clitoral
tumescence, dec frequency with age.
Because REM sleep has the same EEG patterns
as wakefulness, it has been termed “paradoxical
sleep” and “desynchronized sleep.”

Question 38

Narcolepsy

Answer 38

Disordered regulation of sleep-wake cycles; primary characteristic is excessive daytime
sleepiness. May include hypnagogic (just before sleep) or hypnopompic (just before awakening)
hallucinations. The patient’s nocturnal and narcoleptic sleep episodes start off with REM sleep. Cataplexy (loss of all muscle tone following a strong emotional stimulus) in some patients.
Strong genetic component. Treated with daytime stimulants (e.g., amphetamines, modafinil) and
nighttime sodium oxybate (GHB).

Question 39

Circadian rhythm

Answer 39

Driven by suprachiasmatic nucleus (SCN) of hypothalamus. Controls ACTH, prolactin, melatonin, nocturnal NE release. SCN–>NE release–>pineal gland–>melatonin. SCN is regulated by environment (i.e., light).

Question 40

Sleep patterns of depressed pts

Answer 40

Patients with depression typically have the following changes in their sleep stages:
• dec slow-wave sleep
• dec REM latency
• inc REM early in sleep cycle
• inc total REM sleep
• Repeated nighttime awakenings
• Early-morning awakening (important screening question)

Question 41

Integral membrane proteins

Answer 41

contains transmembrane domains composed of alpha helices with hydrophobic amino acid residues such as valine, alanine, isoleucine, methionine, and phenylalanine.

Question 42

Methemoglobinemia

Answer 42

dusky discoloration to the skin (similar to cyanosis) and because methemoglobin is unable to carry oxygen, a state of functional anemia is induced. The blood partial pressure of oxygen; however, will be unchanged in this condition because oxygen’s partial pressure is a measure of oxygen dissolved in the plasma and is not related to hemoglobin function.