Biostat/Behavioral Sci Flashcards Preview

STEP I 2014 > Biostat/Behavioral Sci > Flashcards

Flashcards in Biostat/Behavioral Sci Deck (52):

children engaged in cooperative play are what age? define this type of play.

how is this different from parallel play? at what age does this occur?

-above 4 years old.
plan, assign roles and play together. goal-oriented.
-play next to each other. no interaction. 24-30 months


expectancy bias-def, how to avoid, observation vs intervention study?

researcher or physician knows which subjects are in treatment or placebo group. avoid this with double-blind design. study will usually have an intervention vs observation.


three different ppl are followed over time to see if they have different incidence rates of automobile accidents.
which type of bias? why not recall?

-this is a cohort study. selection bias is the most common type associated with this. def as sample not being representative of population, results in distortion of data.

-recall is a problem with retrospective studies (i.e. case-control study). ppl are asked to remember something


decrease in prevalence leads to what change in NPV? give equation and def

increase NPV
proportion of negative test results that are true negative or probability that a person with a negative test is a true negative


relative risk is calculated how?
when is it typically used?
when does relative risk equal odds ratio?

as the incidence rate of exposed group divided by the incidence rate of the unexposed group (a/(a+b))/ (c/(c+d))
cohort studies
when prevalence is low (i.e. a and c are small) RR= ad/bc or (a/c)/(b/d)


confidence interval
-relation to relative risk
-value if no statistical significance
-values if def statistical significance
-values if may be statistical significance

-range of values with which a specified probability of the means of repeated samples would be expected to fall.
used to judge validity of relative risk ratio. >1 risk risk and <1 decreases risk
- if it includes 1 or 0
-if the values do not overlap
-if the values do overlap


proficiency bias

arises when compairing effects of different treatments administered at different sites. (i.e physicians at a different site make have different levels of skill)


late-look bias-def, aka

occurs when gathering data about some types of severe disease. pts may dies or be in accessible before gathering data.
-loss to follow up


specificity-def, aka, eq

proportion of truly nondiseased persons who have a negative test result, "true negative rate"
-TN/(TN+ FP)


positive predictive value and negative predictive value are affected by



what is percentage of congenital transmission of HIV from mother to child? what about during breastfeedin

-varies with duration but is significant higher than with formula-feeding


when can children younger than 18 be emancipated?

older than 13 yrs and taking care of self (living alone)
serving in the military


when is parental consent not required?

when child is getting treatment for STDs contraception, pregnancy (SEX), addiction (DRUGS), and emergency/trauma (ROCK/&ROLL)


how to treat delirium tremens

disulfiram (conditions pt to stay away from alcohol use)
naltrexone, suportive care


accuracy-def, equation

total percentage of correctly selected. degree to which a measurement represents the true value
-(TP + TN)// (TP+TN+FP+FN)


auditory hallucinations



what psychotic disorder can be mistaken for unipolar disorder

bipolar disorder.
-pt is put on antidepressant meds and becomes hypomanic or manic


loco parentis

physician is empowered to make decisions regarding the pts as a parent would


child at 14 who is married and give birth to a child can make medical decisions for child because? when should DCFS be involved?

she is married. married emancipates and she now has the rights and privileges of a full adult.
involve department of children and family services if the child has no parents or legal guardian present


undifferentiated schizophrenia

pt is clearly schizophrenic but doesn't fall neatly into other subtypes


two eq for attributable risk percent (ARP) aka (2)

=(risk in exposed-risk in unexposed)/risk in exposed
=population attributable risk and attributable rate risk


attributable risk (2 equations)

difference in risk between exposed and non exposed groups
-(a/(a+b)-(c/ (c+d))


name five types of schizophrenia



def disorganized schizophrenia

disorganized speech and behavior and a flat or inappropriate affect


paranoid schizophrenia-def

persecutory delusions and auditory hallucinations.


-positively skewed distribution-def,
the order of mean, median and mode shifts.
-negative skew
-normal skew aka

-small numbers predominate and long slope of curve "tail end" is in the positive direction
-mean is most shifted to negative direction. mean-aka Gaussian or bell shaped; mean=median=mode


how should doctors address possible opiod missuse
"I am concerned about your use of pain med" not "I am concerned that stress and your ability to work are amplifying your pain."

intervene in a nonjudgemental manner
-quote 2 does not address the issue of abuse like quote 1 does


attributable risk

difference in risk between exposed and non exposed groups
-(a/(a+b)-(c/ (c+d))


expectations of child at 1:
social, fine motor, gross motor, language

-social imitating
princer grasp
mama, dada


child at 2 yrs should have
social, fine motor, gross motor and language skills

-imitation of household task
-page turning
-jumping, standing on one foot
-2 word phrases


child at 3 years should have
social fine motor, gross motor, and language skills

-parallel play
-reproducing simple sentences
-tricycle riding
-stair climbing
-simple sentences


child at 4 years should have

-cooperative play, toilet use
-dresses self with help
-running without problems
-complex sentences with pronoun and plural use


how should doctors address possible opiod missuse

intervene in a nonjudgemental manner


over last 4 decades increase and incidence and mortality for which cancer has been seeing in women
-which cancer mortality has remained the same
-which cancer mortality has decreased?

-same=breast (most common non-skin cancer in women
-stomach used to be common but now it's decreased drastically over 1st part of 20th century


define cross over study and washout period

subjects are randomly allocated to a sequence of 2 or more treatment given consecutively.
washout-no treatment period added to limit confounding effects of prior treament


generalized anxiety disorder vs adjustment disorder

-excessive worry over several issues (at least 3) lasting a least 6 months.
-behavior symptoms in response to stressor, symptoms develop 3 month of stressors onset


how to calculate number needed to harm. show calculations of other variables needed as well.
numbers given:
those treated and alive=20 treated and dead=60 (number exposed)
non treated and alive=38
not treated and dead=38 (number exposed)

=1/attributable risk. (AR)
-attributable risk=event rate (treatment)- event rate (placebo)
=(number exposed/total treated))-(number exposed/(total non treated))=(60/80)-(38/76)=0.25
-so NNH=1/attributable risk=1/.25=4


calculate number needed to harm vs number needed to treat?

1/AR vs 1/ARR
Attributable Risk AR=difference in risk between exposed and unexposed. (a/(a+c)-(c/(c+d)).
Absolute Risk Reduction ARR=difference in risk attributable to intervention vs control=(i.e if 8% of ppl without treatment have disease and 2% of ppl with treatment have disease then ARR-8-2=6%) or event rate in placebo group (b/b+d) minus event rate in treatment group (a/a+c); absolute values not a ratio


Berkson's bias is a type of

selection bias. describes a study looking at only hospitalized patients as control group


Pygmalion bias/ self-fulfiling prophecy aka

observer-expectancy bias-researcher beliefs treatment will work and looks for this in pts given treatment vs control group


confounding bias vs effect modifier (def and explain what happens after stratified analysis)

-exposure disease relationship is muddled by effect of extraneous factor. can cause there to be a false association with disease. stratified analysis does not reveal significant difference in RR between groups
-external variable positively or negative impacts observed effect of factor. stratified analysis reveals significant difference in RR between groups



compiling data from several studies to increase power of analysis


sats measured in cohort studies vs case-control studies vs cross-sectional studies

-cohort=incidence measures (relative rate or relative risk)
-C:C=exposure odds ratios
-prevalence odds ratio


likelihood ration positive

sensitivity/ (1-specificity)
test with LR+ greater than 10 significantly increases the likelihood of that a pt will have a disease for which they are being tested for


loss to follow up is a form of? not lead time bias because?

lead time bias-screeenig test diagnoses disease earlier than it would have appeared by natural history alone. make it's look like there's improved survival when really there isn't. fix by measuring "back-end" survival (survial adjusted based on severity of disease at time of diagnosis)

-loss to follow up is a form of selection bias


case fatality rate

number of fatal cases /total number of ppl with disease


type I error vs type II error-aka, measured how, the measurements related to which other measurements?

-false positive error. stating that there is a effect when there isn't one. measured by alpha (probability of making a type I error), related to p. most times p<0.05 or less than 5% chance that this is a type I error.
-false negative error. stating that there is not an effect when there is one. measured using beta (probability of making a type II error); related to statistical power (=1-beta or probability of rejecting null hypothesis when it is false).


ways to decrease beta and increase power

increase sample size, expected effect size, or precision of measurement


chi square test vs two sample t test

-check difference between 2 or more percentages of categorial outcomes (not mean values)
-checks difference between means of 2 groups


increasing prevalence and stable incidence can be attributed to what factor?

anything that prolongs duration of disease. i.e improved quality of care


in a normal bell shaped distribution:
number that are within 1 SD from mean
2 SD
3 SD
what is distribution of remaining percent?

the remaining percent is split with half being above and the other half being below.


easy calculation for True Negatives and False Positives

TN=(Spec)*(# of pts without disease)
FP= (1-Spec)* (# of pts without the disease)