Behavioral/Biostats Flashcards
Odds ratio is used with which of study?
Case-control study
Relative risk is used with which type of study?
Cohort study
Describe Phase IV clinical trials?
Postmarketing surveillance trial of patients after approval of drug/therapy
How is odds ratio calculated?
OR = (ad)/(bc)
How is relative risk calculated?
Risk of developing disease in the exposed group divided by risk of developing disease in the unexposed group; RR = (a/[a+b])/(c/[c+d])
How is relative risk reduction calculated?
RRR = 1-RR
How is attributable risk calculated?
AR = (a/[a+b])-(c/[c+d[)
How is absolute risk reduction calculated?
The difference in risk attributable to the intervention as compared to a control (e.g., if 8% of people who receive a placebo vaccine develop flu vs. 2% of those who receive a flu vaccine, then ARR = 8%-2% = 6% = 0.6)
How is number needed to treat calculated?
NNT = 1/ARR
How is number needed to harm calculated?
NNH = 1/AR
What is another word for “precision” of a test?
Reliability - not necessarily accurate
Does random error reduce the precision or accuracy of a test?
Precision
Does systematic error reduce the precision or accuracy of a test?
Accuracy
What is selection bias?
Nonrandom assignment to participate in a study group
What is measurement bias?
Information is gathered in a way that distorts it
What is procedure bias?
Subjects in different groups are not treated the same
What is observer-expectancy bias?
Researcher’s belief in the efficacy of a treatment changes the outcome of that treatment (aka Pygmalion effect)
What is Berkson bias?
A specific type of selection bias - looking only at inpatients
How is standard error of the mean calculated? *standard error of the mean is an estimation of how much variability exists between the sample mean and the true population mean
SEM = SD/square root of n; SEM decreases as n (sample size) increases
In Gaussian distribution, what percentage of the sample size falls within 1 SD of the mean?
68%
In Gaussian distribution, what percentage of the sample size falls within 2s SD of the mean?
95%
In Gaussian distribution, what percentage of the sample size falls within 3 SDs of the mean?
99.7%
In positive skew distribution, list mean median and mode from greatest to largest
mean > median > mode
In negative skew distribution, list mean median and mode from greatest to largest
mode > median > mean
What is a Type I error?
Rejection of null hypothesis when in reality there is no difference
What is a Type II error?
Acceptance of null hypothesis when in reality there is a difference
When is a t-test used?
Checks differences between means of 2 groups.
When is an ANOVA (analysis of variance) test used?
Checks differences between means of 3+ groups
When is a chi-square test use?
Checks difference between 2 or more percentages or proportions of categorical outcomes (not mean values)
What is quaternary disease prevention?
Identifying patients at risk of unnecessary treatment, protecting them from the harm of new interventions
What are the four core ethical principles?
Respect patient autonomy, beneficence, nonmaleficence, justice
Low birth weight is defined as what?
What are the top three causes of death of infants under 1 year of age?
- Congenital malformations
- Preterm birth
- SIDS
What are the top three causes of death of children 1-14 YO?
- Unintentional injury
- Cancer
- Homicide
What are the top three causes of death of young adults aged 15-24?
- Unintentional injury
- Homicide
- Suicide
What are the top three causes of death of adults 25-34 years of age?
- Unintentional injury
- Suicide
- Homicide
What are the top three causes of death of adults 35-44 YO?
- Unintentional injury
- Cancer
- Heart disease
What are the top three causes of death of adults 45-64 YO?
- Cancer
- Heart disease
- Unintentional injury
What are the top three causes of death of adults over 65 YO?
- Heart disease
- Cancer
- Chronic respiratory
What is a crossover study?
Subjects are randomly allocated to a sequence of 2 or more treatments given consecutively, with a washout period.
What is a “sentinel” event?
An unexpected occurrence involving death or serious physical or psychological injury that requires immediate investigation