BIostat Flashcards
what is an example of continuous data
logical order with values that increase or decrease by the same amount - HR 120 is x2 of HR 60
interval data- no meaningful 0 ( 0 equals something) 0 degree C
ratio data- meaningful 0( 0 means 0) HR is 0
what is an example of discrete data or categorical data
nominal- male female, yes no
ordinal- order = 1,2,3,4,5 pain scales, NYGH i-IV
what is the SD of data
it shows how spread out the value is from the mean, the lwoere the more closer to the mean
what are some charecteristics of normal or gaussian distribution
mean median and mode are the same and are at the center
68% of the values fall within 1 SD and 95 % of the values fall within 2 SD
when is better to use a median and how to even better the measurement
when the data is skewed adn to better add more participants
skewed meaning
data is in the direction of the outlier ( right meaning skewed to the right higher values)
what are independant variables
changed manipulated by the researcher for example drugs, dose, placebos, patients , age etc
what are dependant variables
effected by independant variables
- HF progression, HBA1c, BP cholesterol values
what is the alpha level
alpha level is the max permissable error margin commonly sett at 5%
what is a confidence interval
1- alpha
most of the time 95% confident data is true
if value touches 0 data is not statistically significant
RRR, OR, HR
result is statistically significant if data doesnt cross 1
what is a type I error
error where null is rejected but actually it should be accepted
false positive
** alpha <5 means 95 % correct and 5 % chance for TI error
what is a type II error
where null is rejected shouldve accepted
false negative
Power is used to avoid a type II error
P= 1-b
Power 90% means 90% of avoiding type 2 error
treatment relative risk meaning
if > 1 the treatment is risk with the endpoints
<1 treatment is safer wtih the endpoints than control group
“as likely” as the control group
what is the Relative risk reduction
% of patient less likely to have a disease after treated
“less likely” than control
What is the absolute risk reduction
includes reduction in risk and the incidence rate of the outcome
X amount of pt will benefit from the treatment
can be used to find NNT and NNH
Number needed to treat
1/ ARR round up
example - for every 9 pt who recieve the treatment per year 1 pt can prevent the disease
Number needed to harm
1/ARR rounded down
example- for every 90 pt treated with the treatment 1 patient can get harmed
what is an odds ratio
an event will occur verses the probability that it will not occur
used mostly in case control studies
what and when is hazard ratio used
when there is a disease progression or death
similar to RR
when is a T test used
a student t test is when there is continuous data and 2 variable a treatment and a control group
when is ANOVA or F test used
when there is continuous data with 3 or more samples
Chi square is used when
there is discrete/ categorical data ( such as pain scale) between treatment and control
sensitivity determines
the true positive, higher the sensitivity the better reults
specificity determines
the true negative
the more specific it is the more able it is to differentiate
interntion to treat vs per protocol
ITT is participants who were unable to trat but considered in the trail (all participants)
Per protocol is the study participants
when are forest plots used
in meta analysis
types of medical studies from top to bottom
systematic reviews and meta analysis
randomized control trial
cohort studies
case controlled studies
case series and case reports
expert opinion
which study is prospective
RCT
which studies are retrospective
case control
which study can be both retrospective and prospective
cohort studies
benefits of case controlled study
data is easy to obtain
unethical intervention (pesticide use that caused some problems)
less expensive
*** less reliable
benefits of cohort study
Unethical interventions
** can be influenced by confounders
benefits of RCT
preffered and reliable to find cause and effect
less potential for bias
** time consuming and expensive
what are the various cost analysis
cost-effective
cost minimization
cost utility
cost benefit
what is ECHO
economic
clinical
humanistic outcomes
what are some direct medical costs
Drug prep
hospital admin
office clinic visits
what are some direct non medical costs
travel to the hospital/clinic
caregiver cost
home health aides
what are some indirect costs
lost work time
lost productivity
morbidity
mortality
what are some intangible costs
pain
suffering anxiety
fatigue
what is the average cost effective ratio
average treatment cost to generate successful outcome
incremental cost ratio
C2-C1/E2-E1
if the result is 100 then C2 requires 100$ more for each additional tratment success
what is a cost minimization analysis
> 2 intervention has equal outcome and cost is being compared
what is a cost benefit analysis
comparing benefits and cost of 2 treatment options
measured in dollar outcome in dollar
what is a cost effective analysis
not equal therapeutic but compares two interventions with costs
measured in dollars and outcome is measure in natural units such as %, mmhg BP etc)
cost utility analysis
DALY for disability
QALY for quality of life
measurement of cost but outcome is QALY
