Weeks 1 And 2 Flashcards
Pearson correlation
Linear regression for Gaussian data
-null is that the population correlation is 0 (no linear relationship)
Spearman correlation
Linear ranking method used with extreme values and applied to regression for a more Gaussian look
Regression equation
Y hat= bx+a
When there are Equal SD for regression, blank = blank
B=r
Multivariate
Techniques using multiple factors to remove confounding (except analysis of variance)
Multiple linear regression
For predicting a numeric dependent variable with multiple variables
Logistic regression
Used for 2 levels of dependent variables (yes/no, success/failure, etc)
Proportional hazards
Dependent variable is the time until a certain event
Relative risk
How many times more likely it is for 1 outcome vs another
Odds ratio
An approx of relative risk
Used in logistic regression
Hazard ration
Approx of relative risk, used in proportional hazards
Mean duration of survival
Best if all subjects die; mean amount of time they live
Median duration of survival
How long pts live, works better with censored data
Case fatality rate
% of deaths from condition
5 yr mortality rate
Proportion of deaths in a 5 yr period
Mortality rate per person yrs of observation
of deaths/total pt years (alive and dead)
Survival curves
Kaplan Meier, life table
Censored events
If event of interest doesn’t occur by the end of the study or there is a competing cause of death, etc
True experiment
Randomized design
Crossover trial
Each subjects gets 2 or more tx (each subject is his own control)
Equivalence trial
Shows that 2 tx or equivalent or close enough
Non inferiority trial
1 tx is not worse than an existing tx
Quasi experimental design
Strong element of control BUT no random assignment of individuals to groups
Single subject multiple baseline
Quasi exp
-many observations, intervention, many observations
Group multiple baseline
Quasi exp
-multiple baseline, intervention to group, multiple observations
Community trial
- quasi
- unit is the community but unit of analysis is the individual
- need verifiably comparable community
- randomly assigned intervention
Observational design
No intervention, only observation
-researcher does NOT randomly assign or control for various conditions
Case report
Details of 1 interesting case
Case series
Collection of case reports to show a pattern
Ecological/correlational
Look at a group and try to draw causal relationship
Ex: try to draw assoc between rate of homicide/suicide in London and the mean mental illness score in the boroughs
Cross sectional design/prevalence study
Exposure and disease status measure at a GIVEN time
Ex: ask if pt uses condoms CURRENTLY and see if they have an STD
Con: don’t know if exposure (use of condom) was before contraction of disease or started using after contracting disease
Case control
Group of cases with disease compared to group without disease
Cohort study
Group of initially healthy pts are evaluated for exposure status and then followed to see what happens
Attrition bias
Loss of subjects –> distortion of experiment’s effects
-at least 80% of subjects should complete trial
Allocation concealment
People assessing elegibility should not be able to know what group the next entering patient will be assigned to
Rating bias
Inaccurate responses because of beliefs, expectations
File drawer bias
Non significan small studies end up being filed instead of published; can also be done on purpose by drug companies
Patient oriented outcomes
Disability, pain, additional surgeries all are things patients would care about