Quiz 2 Deck 2 Flashcards
what is MDC?
Minimal Detectable Change: amount of change that just exceeds the SEM
what is MCID?
Minimal Clinically Important Difference: smallest difference in measurement that signifies an important change in pt’s condition
for outcome measurement properties that are easy to interpret, what do MDC & MCID indicate?
- below MDC = not stat significant & not important.
- btwn MDC & MCID = stat significant, but not important.
- above MCID = stat sig & important
for outcome measurement properties that are challenging to interpret, what do MDC & MCID indicate?
- below MCID = not stat significant & not important.
- btwn MCID & MDC = important change but cannot be distinguished from measurement error.
- above MDC = stat sig & important
what is pooled standard deviation
calculation of effect size for 2 groups w/in a trial
3 ways to calculate effect size for single group studies
- effect size, ES = (mean posttest - mean pretest) / SDpre
- standardized response mean, SRM = (mean post - mean pre) / SDchange
- Guyatt’s = MCID / sqrt(2 x MSE)
what does Cohen’s d interpret?
effect size & SRM between control & experimental groups
Cohen’s d criteria
- 8 = large treatment effect.
- 5 = moderate
- 2 = small
if difference in means = variance, effect size is ___
large
if difference in means > variance, effect size is ___
large
if difference in means is 50% of variance, effect size is ___
mod
effect size correlation (r)
r = d / sqrt(d^2 - 4)
experimental success rate (what it means & how to calc)
how likely the Rx group will have a successful outcome.
exp success rate = 0.5 + r/2
control success rate (what it means & how to calc)
how likely the Ctrl group will have a successful outcome.
exp success rate = 0.5 - r/2
relative success rate
= exp success rate / ctrl success rate
what is benefit increase?
how much the intervention increases the chance of a desirable event
how is relative benefit increase (RBI) calculated?
[(% therapy group w/ outcome - % control w/ outcome) / % control w/ outcome] x 100%
how is absolute benefit increase (ABI) calculated?
% therapy group w/ outcome - % control w/ outcome
how is number needed to treat (NNT) determined?
1/ABI or 1/ARR
what is risk reduction?
how much the intervention reduces the risk of an unwanted event
how is relative risk reduction (RRR) calculated?
[(% ctrl w/ problem - % therapy w/ problem) / % ctrl w/ problem] x 100%
how is absolute risk reduction (ARR) calc?
% ctrl w/ problem - % therapy w/ problem
what qualifies as “benefit” or “harm”?
benefit: # subjects who must receive rx to produce 1 (+) outcome OR avoid 1 adverse event.
risk: # subjects who must receive rx to produce 1 adverse event.
what is EER
experimental group event rate (% subjects w/ outcome)
what is CER
control group event rate (% subjects w/ outcome)
what does it mean if NNT = 1
every pt will have the successful outcome
what does it mean if NNT = 100
1 out of every 100 pts will have desired outcome
what is an important detail to pay attention to when considering NNT in a study?
how they define “successful outcome”
what is NNH?
number needed to harm: # harmed by the treatment
what does it mean if NNH = 8?
1 out of 8 will be harmed by Rx
