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TERM 3- Premidterm > First Aid- Epidemiology and Biostatistics > Flashcards

First Aid- Epidemiology and Biostatistics Flashcards

1
Q

define cross-sectional study

A

assessing frequency of disease and frequency of risk-related factors- ex. Surveys
(what’s happening)

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2
Q

define case-control study

A

-compares group with disease and group without disease
-do odds of prior exposure/risk factors differ by disease state
(what happened)

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3
Q

define cohort study

A
  • compares group with exposure to group without exposure
  • is exposure related to LATER developed disease
  • prospective or retrospective
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4
Q

define twin concordance study

A
  • compares frequency of disease between identical and fraternal twins
  • higher the concordance –> more genetic the factors, the lower –> more environmental factors
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5
Q

define adoption study

A

compares siblings raised by biological v adaptive parents to measure heritability and influence of environmental factors

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6
Q

define triple blind study

A
  • single is patients don’t know what treatment they are getting
  • double is patients and doctors not knowing
  • triple is patients, doctors, and researchers/statisticians not knowing
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7
Q

purpose of phase I trials

A

(is it safe)

assesses safety, toxicity, pharmodynamics and pharmacokinetics (discover safe dose range)

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8
Q

purpose of phase II trials

A

(does it work)

assesses treatment efficacy, optimal dosing, adverse effects

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9
Q

purpose of phase III trials

A

(is it better than what there is)

compare treatment to current standard of care

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10
Q

purpose of phase IV trials

A

(can it stay)

  • drug is on the market, although can be withdrawn
  • detects rare, long-term adverse effects
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11
Q

define drug/therapy efficacy

A

how well the drug/therapy works under good experimental conditions
(internal validity)

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12
Q

define drug/therapy effectiveness

A

how well the drug/therapy works under real world conditions

generalizability, external validity

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13
Q

sensitivity, aka (1)

define SN-N-OUT

A

1- true positive rate

2- high sensitivity, if negative, r/o disease

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14
Q

specificity, aka (2)

define SP-P-IN

A

1- true negative rate

2- high specificity, if positive, rules in disease

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15
Q

pretest probability varies directly with…

A

positive predictive value, prevalence

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16
Q

pretest probability varies inversely with…

A

negative predictive value

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17
Q

LR+ formula and the desired/significant value

A

LR+ = sensitivity / (1 - specificity) = TP rate / FP rate

LR+ > 10 indicates useful diagnostic test

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18
Q

LR- formula and the desired/significant value

A

LR- = (1 - sensitivity) / specificity = FN rate / TN rate

LR- < 0.1 indicates useful diagnostic test

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19
Q

LRs (+ or -) multiplied by (1) estimates (2)

A

1- pretest odds
2- posttest odds
PostOdds = LR * PreOdds

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20
Q

prevalence = …

A

prevalence = (number of cases) / (total population)

[at a point in time]

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21
Q

incidence = …

A

incidence = (number of new cases) / (number of people at risk)
[during a given time period]

22
Q

high prevalence indicates what values of PPV and NPV

A

(positive/negative predictive value)

  • high PPV
  • low NPV
23
Q

in acute diseases prevalence is (=/>) incidence

in chronic disease prevalence is (=/>) incidence

A

Acute: P ~= I

Chronic P > I

24
Q

define Odds Ratio (OR)

A

odds of certain exposure given an event (disease) / odds of exposure in absence of exposure

-usually used in case-control studies

25
Q

define Relative Risk (RR) and the indications of all 3 results

A

risk of developing disease in exposed group / risk of developing disease in non-exposed group

-usually used in cohort studies

RR = 1, no association with exposure/disease
RR > 1, exposure associated w/ inc disease occurrence
RR < 1, exposure associated w/ dec disease occurrence

26
Q

define Attributable Risk (AR)

A

difference in risk between exposed group and non-exposed group

27
Q

define number needed to treat, what is ideal value

A
  • number of people that need to be treated for 1 patient to benefit
  • low number is best
28
Q

define number needed to harm, what is ideal value

A
  • number of people that need to be exposed to risk factor for 1 patient to be harmed
  • high number is best
29
Q

positive skew has peak on (R/L) side

compare values of mean, mode, median

A
  • L sided peak (L modal) – R sided tail

- mean > median > mode

30
Q

negative skew has peak on (R/L) side

compare values of mean, mode, median

A
  • R sided peak (R modal) – L sided tail

- mode > median > mean

31
Q

define null hypothesis (H0)

A

no association between disease and risk factor (hypothesis of no difference / relationship)

32
Q

define alternative hypothesis (H1)

A

some association between disease and risk factor (hypothesis of some difference / relationship)

33
Q

define selection bias

A

nonrandom sample or treatment allocation that is not representative of target population

  • usually a sampling bias > treatment allocation
  • during recruitment participants phase
34
Q

define recall bias

A

awareness of disorder alters subject’s recall

  • common in retrospective studies
  • during actual performing of study phase
35
Q

define measurement bias

A

info is gathered is systemically distorted manner: hawthorne effect, faulty equipment
-during actual performing of study phase

36
Q

define Hawthorne effect

A

study participants change behavior (improved health behaviors) when they know they are being observed

37
Q

define procedure bias

A

subjects in different groups are not treated same (treatment group has more specialized care than placebo group)
-during actual performing of study phase

38
Q

define observer-expectancy bias

A

aka Pygamalion effect, researcher expects treatment group to do better and has more positive view or documents more positive outcomes
-during actual performing of study phase

39
Q

define confounding bias

A

when a factor contributes to both an exposure and outcome, but not necessarily on the causal pathway

  • ex. inc Pulmonary disease in coal miners > general population, but also higher smoking rates in in coal miners
  • during interpretation of results phase
40
Q

define lead-time bias

A

early detection of disease is confused with inc survival of people with disease

  • fix by adjusting survival to severity of disease at time of diagnosis
  • during interpretation of results phase
41
Q

define length-time bias

A

screening test detects disease with long latency period, although those with shorter latency are symptomatic earlier

  • ex. slow progressive cancer is more likely to be detected by screening test than rapid progressive cancer
  • during interpretation of results phase
42
Q

type I error

A

false positives (aka α error)

43
Q

type II error

A

false negative (aka β error)

44
Q

Power (of a study) = ….

A

P = 1 - β
β- false negatives

inc Power (dec β) by inc sample size, inc expected effect size, inc precision of measurement

45
Q

what is the ideal/pre-judged α value, what is compared against, and what does it mean

A

α = 0.05

  • indicates 95% confidence interval
  • if p < α / 0.05 => 5% chance the data is random, statistically significant results
46
Q

what is the ideal CI

A

(confidence interval)

  • 95%
  • Odds Ratio with confidence interval that doesn’t include => statistically significant results
47
Q

define meta-analysis

A

statistical analysis of multiple studies to generate more precise estimate of the size of an effect, estimate heterogeneity between studies, and improve generalizability of study findings

48
Q

define t-test (statistical test)

A

compares differences of means between two groups in a study (often men and women)

49
Q

define ANOVA (statistical test)

A

compares differences in means between three or more groups (often ethnicity)

50
Q

define Chi-square (statistical test)

A

compares differences between two or more groups by percentages/proportions of categorical outcomes

51
Q

Pearson correlation coefficient = …… (include its characteristics)

A

r, between -1 and 1

  • positive => positive correlation, negative => negative correlation
  • r = 0 => no correlation
  • r^2 = variance

TERM 3- Premidterm (20 decks)

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