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Flashcards in Behavioral Science Deck (81):

Cross sectional Study

Collects data from a group of people to asses frequence of disease at a particular time

  • Measures prevalence
  • does not establish causality


What is happening?



Case-control study

Compares a group of people with disease to a group without disease

  • looks for prior exposure or risk factor
  • Measures: Odds Ratio


Asks "What happened?"


Cohort study

Compares a group witha given exposure or risk factor to a group without such exposure

  • Looks to see if exposure increases the liklihood of disease
  • Can be prospective ( who will develop the disease?) or retrospective ( who developed the disease?)
  • Measures: Relative risk


Twin concordance study

Compares the frequency with which both monozygotic twins or both dizygotic twins develop same disease

  • measures heritability and influence of environmental factors
  • nature vs. nurture


Adoption Study

Compares siblings raised by biological vs. adoptive parents

  • measures heritability and influence of environmental factors


Clinical Trial

Experimental study involving humans

  • Compares therapeutic benefit of 2 or more treatments or tx vs. placebo
  • quality improves when study is randomized, controlled or double blinded
  • Triple-blinded= researchers are blinded


Drug Trials

  • Phase I: assess safety, toxicity, and pharmacokinetics
  • Phase II: assess treatment efficacy, optimal dosing, adverse effects
  • Phase III: compares new treatment to current standard of care
  • Phase IV: Detects rare or long term adverse effects


Evaluation of diagnostic test

Uses 2x 2 tables comparing test results with actual presence of disease

  • True positive
  • False positive
  • True negative
  • False negative



True-positive rate

  • proprotion of all people with disease who test positive
  • probability that a test detects disease when disease is present
  • 100% = rule out disease & low false negative rate
  • TP/ (TP+FN)
  • high Sensitive test when Negative, rules out disease



True Negative rate

  • Proprotion of all people without disease who test negative
  • probability that a test indicates non-disease when disease is absent
  • Value approaching 100%= desirable for ruling IN disease (low false positive)
  • TN/ (TN +FP)
  • Specific Test when Positive, rules IN disease


Positive predictive value

Proprotion of positive test results that are true positive

  • Probability that person actually has the disease given a positive test result
  • TP/ (TP+FP)
  • high pretest probability--> high PPV


Negative Predictive value

Proprotion of negative test results that are true negative

  • proprotion that person actually is disease free given a negative test result
  • TN/ (FN+TN)
  • high pre-test probability--> low NPV


Incidence vs Prevalence

  • Incidence: looks at NEW cases
    • #new cases/ population at risk
  • Prevalence: looks at all CURRENT cases
    • # existing cases/ population at risk



Odds Ratio

Odds that the group with the disease was exposed to a risk factor divided by the odds that the group without the disease (control) was exposed

  • Used in case control study


Relative Risk

Risk of deeloping disease in the exposed group divided by risk in the unexposed group

  • typically used in cohort study
  • if prevalence is low, RR= OR


Relative Risk Reduction

Proportion of risk reduction attributable to the intervention as compared to a control.

  • RRR=1-RR


Absolute Risk reduction

Difference in risk (not proportion) attributable to the intervention as compared to a control


Attributable Risk

Difference in risk between exposed and unexposed groups, or the proportion of disease occurances that are attributable to the exposure


Number needed to treat

Number of patients who need to be treated for 1 patient to benefit

  • 1/ (absolute risk reduction)


Number needed to harm

Number of patients who need to be exposed to a risk factor for 1 patient to be harmed

  • 1/ (attributable risk)



  • Precision: consistency and reproducibility of a test (reliability)
  • absence of random variation
  • random error reduces precision in a test
  • increased precision= decreased standard deviation



Trueness of test measurements

  • absence of systematic error or bias in a test
  • Systematic error: reduces accuracy in a test


Selection Bias

Nonrandom assignment to participate in a study group

  • Berkson bias: study looking only at inpatients
  • Loss to follow up: studying a disease with early mortality
  • Healthy workers and volunteer bias: study populations are healthier than general public

Reduce bias

  • Randomization
  • Ensure choice of right comparison group


Recall Bias

Awareness of disorder alters recall by subject

  • common in retrospective studies
  • Strategy to reduce bias: decrease time from exposure to follow up


Measurement Bias

Information is gathered in a way that distorts it

  • Hawthorne effect: groups who know they are being studied behave differently
  • Reduce bias: use placebo control groups with blinding to reduce influence of participants


Procedure Bias

Subjects in different groups are not treated the same


Observer expectancy bias

researcher's belief in efficacy of a treatment changes the outcome of treatment


Confounding bias

When a factor is related to both the exposure and outcome, but not on the causal pathway

  • factor distorts or confuses effect of exposure on outcome
  • Strategy to reduce bias: multiple/repeat studies, cross-over studies, matching studies


Lead time bias

Early detection is confused with increase in survival

  • early detection makes it seen as though survival has increased but natural history of disease has not changed
  • Strategy to reduce bias: measure "back-end" survival (adjust survival according to severity at time of disease)


Measure of central tendancy

  • Mean: sum of values/total number of values
  • Median: middle value of a list sorted from least to greatest
  • Mode: most common value


Measure of Dispersion

  • Standard deviation: how much variability exists from mean in a set of values
  • Standard error of the mean: estimation of how much variability exists between the sample mean and true population mean


Normal Distribution

  • Gaussian, bell shaped curve
  • Mean=Median=Mode


Bi-modal distribution

Suggest 2 different populations


Positive skew

mean > median > mode

asymmetry with longer tail on right


Negative skew


asymmetry with longer tail on left


Null hypothesis

Hypothesis of no differences

Ie; no association between the disease and the risk factor int he population


Alternative hypothesis

Hypothesis of some difference

ie. there is some difference between teh disease and the risk factor in the population


Corret result in hypothesis testing

  • There is an effect or difference when one exists
    • null hypothesis rejected in favor of alternative hypothesis
  • There is not an effect or difference when none exists
    • null hypothesis is not rejected


Type I Error

Stating that there is an effect or difference when none exists (false positive)

  • null hypothesis incorrectly rejected
  • (Alpha) probability of making a type I error
  • probability is judged against a level of significance
  • (p<0.05) = there is less than a 5% chance that the data will show something that is not really there


Type II error

Stating that there is not an effect or difference when one exists

  • null hypothesis is not rejected when it is in fact false
  • false negative
  • increase sample size --> increase power
  • (Beta) is probably of making a type II error
  • related to power
  • (1-beta) is the probability of rejecting the null hypothesis when it is false


Confidence Interval

Range of values in which a specified probability of the means of repeated samples would be expected to fall

  • CI= range from (mean-Z(SEM) to (mean +Z(SEM)
  • 95% CI (p=0.05) is often used
  • if the CI between 2 groups do not overlap= significant difference exists
  • if CI between 2 groups overlap= no significant difference exists



t - test

checks difference between MEANS of 2 groups

"Tea is meant for 2"



Checks difference between mean of 3 or more groups

Analysis of variance (3 words)


Chi squared

Checks difference between 2 or more percentages or proportions of categorical outcomes (not mean values)

  • Comparing the percentages of members of 3 different ethnic groups who have essential HTN


Pearson correlation coefficient (r)

  • r is always between -1 and +1
  • closer the absolute value of r is to 1, the stronger the linear correlation between the 2 variables
  • Postive r value= positive correlation
  • negative r value= negative correlation
  • r2= coefficient of determination


Respect patient autonomy

obligation to respect patient as individuals

  • truth telling, confidentiality
  • creat conditions necessary for autonomous choice ( informed consent)
  • honor their preference in accept or not accepting medical care



Physician have a ethical duty to act in the patient's best interest

may conflict with autonomy or what is best for society



"Do no harm"

must be balanced against beneficence.

If benefits outweigh the risks, a patient may make an informed decision to proceed



To treat persons fairly and equitably


Informed consent

A process that legally requires

  • Disclosure: discussion of pertinent information
  • Understanding: ability to comprehend
  • Mental capacity: unless incompetent
  • Voluntariness: freedom from coercion and manipulation


  • pt lacks decision making capacity or is legally incompetent
  • implied consent in an emergency
  • therapeutic privilege: withholding information when disclosure would severely harm the patient or undermind informed decision-making capcity
  • waiver: patient waives the right of informed consent


Consent for minors

minor <18 yo

  • patient consent should be obtained unless minor is legally emancipated
  • situations in which parental consent is usually not required
    • Sex: contraceptinon, STDs, pregnancy
    • Drugs (addiction)
    • Rock & Roll (trauma, emergency)


Decision making capacity

Physicians must determin where the pt is psychologically and legally capable of making a particular health care decision

  • patient >18 yo or otherwise legally emancipated
  • patient is informed (knows and understands)
  • patient makes and communicates a choice
  • decision remains stable over time
  • decision is consistent with patient's values and goals
  • decision is not a result of delusions or hallucinations


Advanced Directives

Instructions given by a patient in anticipation of the need for a medical decision

  • oral advance directive: incapacitated patient's prior oral statements commonly used as a guide. More valid if the patient was informed, specific, and repeated to multiple people


Living will

Describes treatments the patient wishes to recieve or not recieve if he or she loses decision making capacity


Medical Power of Attorney

Patient designates an agent to make medical decisions in the event that he or she loses decision  making capacity

  • Can be revoked any time patient wishes
  • more flexible than living will


Surrogate decision maker

If an incompetent patient has not prepared an advanced directive, indiviuals who know the patient must determine what the patient would have done if he or she were competent



Respects patients privacy and autonomy.


  • potential physical harm to others in serious and imminent
  • likelihood of harm to self is great
  • no alternative means exists to warn or protect those at risk
  • physicians can take risk to prevent harm
  • Examples: reportable disease, child or elder abuse, impaired drivers, suicidal pt


Ethical Situation:

Patient is not adherent

Attempt to identify the reason for nonadherence and determine willingness to change


Ethical Situation:

Patient desires an uncessary procedure

Attempt to understand why the patient wants the procesure and address the underlying concern.

  • Do not refer to another physician. 
  • Avoid preforming uncessary procedures


Ethical Situation:

Patient has difficulty taking medications

Provide written instructions. Attempt to simplfy treatment regimens. Use teach back methods


Ethical Situation:

Family members ask for information about patient's prognosis

avoid discussing with relatives without permission of the patient


Ethical Situation:

A patient's family member asks you not to disclose the results of a test if the prognosis is poor because the patient will not be able to handle it

attempt to identify why the family member believes such information would be detrimental to patient's condition.

Explain that as long as the patient has decision making capacity and does not indicate otherwise, communication concerning healthcare will not be withheld


Ethical Situation:

a chid wishes to know more about his or her illness

Ask what the parents have told the child. Parents of child can decide what information can be relayed about the illness


Ethical Situation:

17 yo girl is pregnant and requests an abortion

Many states require parental notification or consent for minors for an abortion. Unless she is at medical risk, do not advise patient to have an abortion


Ethical Situation:

15 yo girl is pregnant and wants to keep the child. Her parents wnat you to tell her to give the child up for adoption

Patient retains the right to make decisions regarding her child, even if her parents disagree.


Ethical Situation:

Terminally ill patient requires physician assistance in ending own life

Most states: refuse involvement in any form of physician assisted suicide. Physicians may, presecribe medically appropriate analgesics that conincidentally shorten's patient's life


Ethical Situation:

Patient is suicidal

assess the seriousness of the threat.

  • Serious: suggest patient remain in the hospital
  • patient can be hospitalized involuntarily if he/she refuses


Ethical Situation:

Patient states that he or she finds you attractive

Ask direct, close ended questions and use a chaperone if necessary

  • Romantic relationships are never appropriate


Ethical Situation:

Woman who had a mastectomy says she now feels "Ugly"

Find out why patient feels this way

  • Do not offer falsely reassuring statements (you still look good)


Ethical Situation:

Patient is angry about the amount s/he is spending in the waiting room

  • Acknowledge the patient's anger but do not take it personally
  • Apologize for the inconvenience
  • Stay away from efforts to explain the delay


Ethical Situation:

Patient is upset with teh way s/he was treated by another doctor

Suggest that the patient speak directly to that physician regarding concerns


Ethical Situation:

Drug company offers a 'referral fee' for every patient that a physician enrolls in a study

Eligible patients who may benefit from the study may enroll but is never acceptable for physcian to receive compensation from a drug company. Patients must be told about the existence of a referral fee


Ethical Situation:

Physician orders an invasive test for the wrong patient

No matter how serious or trivial a medical error, physician is obligated to inform a patient that a mistake has been made


Ethical Situation:

Patient requires a treatment not covered by his/her insurance

Never limit or delay care because of expense in time or money. Discuss all treatment options even if some are not covered by insurance companies


Apgar score

assessment of newborn vital signs following labor via 10 point scale evaluated at 1 min and 5 min

  • Appearance
  • Pulse
  • Grimace
  • Activity
  • Respiration

>7 good, 4-6 assist and stimulate, <4 resuscitate


low birth weight

Defined as <2500g

  • associated with increased risk of SIDS and increase in overall mortality
  • complications: infections, repiratory distress syndrome, necrotizing enterocolitis, intraventricular hemorrhage, and persistent fetal circulation



0-12 mo


  • Primitive reflexes disppear (Moro 3mo, Palmar 6mo, Babkinski 12mo)
  • Posture (Lifts head by 1 mo, rolls by 6 mo, crawls by 8, stands by 10 mo, walks by 12 mo)
  • Picks up toy (6mo)
  • Pincer grip by 10 mo
  • Points by 12 mo


  • social smile by 2 mo
  • Stranger anxiety by 6 mo
  • Separation anxiety by 9 mo


  • Orients: voice (4 mo) name & gestures (9 mo)
  • Object permanence (9 mo)
  • Oratory: mama and dada (10mo)


Milestone 12-36 mo


  • climbs stairs (18mo)
  • cubes stack (age x 3)
  • Cultured: feeds self by 20 mo
  • Kicks ball by 24 mo


  • Recreation: parallel play (12 mo)
  • Rapprochement: moves frome and returns to mom (24 mo)
  • Realization: core gender identity (36 mo)


  • Words: 200 words by age 2, 2 word sentences


Milestone 3-5yo


  • Drive: tricycle (3 years)
  • Drawings: stick figures by 4y
  • Dexterity: hops on 1 foot (4 y), uses buttons/ grooms self by 5


  • Freedom: comfortably spends part of day away from mother (3 yr)
  • Friends: cooperative play by 4


  • 1000 words by 3
  • uses complete sentences
  • Legends: can tell detailed stories by 4y


Changes in eldery

  • Men: slower erection/ ejaculation, longer refractory period
  • Women: vaginal shortening, thinning, dryness
  • Sleep: decreased REM and slow wave sleep, increase sleep onset latency and increase early awakeninng
  • increased suicide rate
  • decrease vision, hearing, immune response, bladder control
  • decrease renal, pulmonary, GI funtion
  • decrease muscle mass, increase fat