Behavioral science Flashcards
Lead-time bias
prolonged survival in patients with screening test
- Earlier diagnosis without improved prognosis
Recall bias
Inaccurate patient recall of past exposure
- ex: what caused cancer?
Observer bias
Investigator decision changed by prior knowledge of exposure status
Type 1 error
Reject null hypothesis when it’s true
- Found a difference when there isn’t one)
P-value
Probability of making type 1 error
- Accepted at P< 0.05 (5% chance)
Type 2 error
Failure to reject null hypothesis when it’s false
Beta
Probability of making a type 2 error
Power
1- beta
ex: beta= 20% chance of making type 2 error;
- power= 80% chance of rejecting truly false null hypothesis
Case-control study
Compares those with disease to those without disease
- Measures Odds Ratio (OR):
(exposed with disease/diseased)/ (exposed without disease/ all without disease)
Cohort study
Compares group with exposure/risk factor to group without exposure
- Measures relative risk (RR):
Risk of disease with exposure/ risk of disease without exposure
Clinical trial phases
Phase I= safety, toxicity, PK
Phase II= efficacy, dosing, AEs
Phase III= comparison to standard tx
Phase IV= rare, long-term AE (post-marketing)
Case-fatality rate
Fatal/ (Fatal + nonfatal cases)
Sensitivity
Test detects disease when disease present
- Screening tool for disease with low prevalence
True positives / (TP + False negatives)
Specificity
Test indicates non-disease when disease is absent (ruling in disease)
- Confirmatory test after positive screen
True negatives/ (TN + False positives)
Positive predictive value
Proportion of positive test results that are truly positive: TP/ (TP+ FP)
Negative predictive value
Proportion of negative results that are truly negative
TN/ (FN + TN)
Attributable risk
How much disease was due to exposure?
Disease rate with exposure / disease rate without exposure
- Ex: 21% lung cancer risk in smokers, 1% in non-smokers= 20% attributable risk
OR:
Adverse Event rate (tx) - Adverse event (placebo)
Absolute risk reduction
Event rate (control) - Event rate (treatment group)
Number needed to treat
Number to treat for 1 patient to benefit:
1/(absolute risk reduction)
ARR= event rate (control)- Event rate (treatment group)
Number needed to harm
Number needed to treat for 1 patient to have adverse event:
1/ (attributable risk)
Late-look bias
information gathered at inappropriate time (ex: survey to study fatal disease after people will have died of disease)
Procedure bias
Subjects in different groups not treated the same
more attention paid to tx group
Observer-expectancy effecct
Researcher’s belief in efficacy of treatment changes outcome of treatment
Hawthorne effect
Group being studied changes behavior because they know they are being studied
Standard error of the mean (SEM)
SD/ square root (sample size)
- SEM is powered by the size of the population
- Larger study indicates the standard deviation is closer to what would be seen in the general population
Positive skew
Mean skewed positively:
- Mean > Median > mode
Negative skew
Mean skewed negatively
- Mean < Median < mode
Confidence interval
Range from [mean- Z(SEM)] to [mean + Z(SEM)]
95% CI for a mean difference including 0–> H0 is not rejected
95% CI for a OR or RR including 1, H0 is not rejected
- H0= null hypothesis
- H1= alternative hypothesis
95% CI; Z=1.96
99% CI; Z= 2.58
T-test
Difference between means of 2 groups
2-sample T-test= determine if means of 2 populations are equal: need:
- 2 mean values
- Sample difference (standard deviation)
- Sample size
ANOVA
Analysis of variance
- Checks difference between mean of 3+ groups
Chi-square
Difference between 2+ percentages or proportions (NOT mean values)
x^2= compare percentages/proportions
Multiple linear regression
Model linear relationship between dependent variable and 2+ independent variables
ex: alcohol and tobacco use and incidence of gastric cancer
Pearson’s correlation coefficient (r)
Measures strength of linear regression line (closer value is to r, stronger linear correlation)
Ranges between -1 and 1 (depending on direct(+) or inverse(-) relationship between two factors
Apgar score
Assess newborn vital signs via 10-point scale at 1 and 5 minutes Appearance Pulse Grimace Activity Respiration
> = 7: good
4-6: assist, stimulate
< 4: resuscitate
- Low birth weight < 2500 g
- Premature, intrauterine growth retardation
- Increased risk of SIDS, mortality, developmental problems
Birth-3 months milestones
Motor:
- Rooting reflex
- Hold head up
- Moro reflex disappears
Social:
- Social smile
Verbal/cog:
- Orients, responds to voices
7-9 months
Motor:
- sits alone, crawls
- Transfers toys from hand to hand
Social:
- stranger anxiety
Verbal/cog:
- Responds to name, simple instructions
- Uses gestures, plays peek-a-boo
12-15 months
Motor:
- walks
- Babinski sign gone
Social:
- Separation anxiety
Verbal/cog:
- Few words
12-24 months
Motor:
- climbs stairs
- stacks 3 blocks at 1 year, 6 at 2 (3/year)
Social:
- Rapprochement (moves away from, returns to mother)
Verbal/cog:
- 200 words and 2-word phrases
24-36 months
Motor:
- Feeding self with fork and spoon
- Kicks ball
Social:
- Core gender identity, parallel play
Verbal/cog:
- toilet training
3 years
Motor:
- Rides Tricycle
- Copies line, circle drawings
Social:
- Comfortably spends part of day away from mom
Verbal/cog:
- 900 words, complete sentences
4 years
Motor:
- Uses buttons, zippers, grooms self (brush teeth)
- Hops on 1 foot
- Makes simple drawings
Social:
- Cooperative play, imaginary friends
Verbal/cog:
- Detailed story telling, uses prepositions
Circadian rhythm
Suprachiasmatic nucleus (SCN) of hypothalamus - Controls ACTH, prolactin, melatonin, nocturnal NE release
SCN–> NE release–> pineal gland–> melatonin
SCN regulated by environment (light)
