Behavioral Science Flashcards
Odd Case
observational and retrospective
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
Relative Cohort
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)
Cross sectional
prevalence study
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.
Clinical trial
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
Cross over study
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
Sensitivity
Used for screening test with low prevalence.
=1-FN rate
SNOUT= Sensitivity rules OUT
Specificity
Used for confirmatory test after a positive screening test.
=1-FP
SPIN=specificity rules IN
PPV
PPV varies directly with prevalence or pretest
probability: high pretest probability–>high PPV
NPV
NPV varies inversely with prevalence or pretest
probability: high pretest probability–>low NPV
Attributable risk
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)
Number needed to tx
Number of patients who need to be treated for 1
patient to benefit. Calculated as 1/absolute risk
reduction.
Absolute risk reduction
c/(c+d)–a/(a+b)
Absolute reduction in risk associated with a
treatment as compared to a control
Number needed to harm
Number of patients who need to be exposed
to a risk factor for 1 patient to be harmed.
Calculated as 1/attributable risk.
Precision
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.
Accuracy
The trueness of test measurements (validity). The
absence of systematic error or bias in a test.
Systematic error-reduces accuracy in a test.
Sampling bias
Subjects are not representative of the general
population; therefore, results are not
generalizable. A type of selection bias.
Late look bias
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)
Procedure bias
Subjects in different groups are not treated the
same-e.g., more attention is paid to treatment
group, stimulating greater adherence
Lead time bias
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)
Observer expectancy effect
Occurs when a researcher’s belief in the efficacy
of a treatment changes the outcome of that
treatment
Expecting results your way, lol
Hawthorne effect
Occurs when the group being studied changes
its behavior owing to the knowledge of being
studied
Mean
average of all values
Median
falls right in the middle of all values
mode
the number that occurs most frequently
Normal distribution
Gaussian, also called bell-shaped.
Mean =median= mode.
Positive skew
Typically, mean > median > mode.
Asymmetry with longer tail on right.
Mode is least affected by outliers in the sample.
Negative skew
Typically, mean <mode.
Asymmetry with longer tail on left.
Type 1 error (alpha)
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.)
Type 2 error (beta)
Also known as false-negative error.
Beta =you were blind to a difference that did
exist-e.g., (setting a guilty man free).
Confidence Interval
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.
t test
Checks difference between the means of 2
groups.
ANOVA
Checks difference between the means of 3 or
more groups.
Chi-squared
Test checks difference between 2 or more
percentages or proportions of categorical
outcomes (not mean values).
Disease prevention
PDR:
Prevent (vacciations)
Detect (screen)
Reduce disability (treat)
APGAR
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 (
Grief
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.
REM Sleep
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.”
Narcolepsy
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).
Circadian rhythm
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).
Sleep patterns of depressed pts
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)
Integral membrane proteins
contains transmembrane domains composed of alpha helices with hydrophobic amino acid residues such as valine, alanine, isoleucine, methionine, and phenylalanine.
Methemoglobinemia
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.
