Logistic Regression and Survival Analysis- Austin

How does a logistic distribution compare to normal distribution?

How does a logistic distribution compare to normal distribution?

• look similar BUT shape on the edges are different

  • aka homoscedasticity

When the dependent variable is continuous we use linear regression, and when the dependent variable is discrete we use _________________.

logistic regression

What are the pros and cons of clinical categories?

pros: quickly make distinction bc we have cutoffs

cons: can be misleading

For binary logistic regression it is the appropriate method when an outcome variable consists of only ____ categories.

2 (yes/no)

Probabilities must be constrained between ___ and ____ in binary logistic regression.

0 and 1

What is logit or “log-odds” ?

the natural log of the odds of the event of interest occurring

In logistic regression we cannot use OLS like multiple regression, so instead we use what?

MLE

In MLE we are looking at the ____________ ability for a variable to effect an outcome.

maximum

In logistic regression, we cannot use R² like multiple regression, instead we use what?

chi-square

Is binary logistic regression nonparametric or parametric?

nonparametric

In binary logistic regression, in the confidence interval if it crosses what number is the variable insignificant?

1

What does it mean when a regressor has a coefficient estimate that has a negative sign?

variable decreases probability

What is this equation used for?

Binary logistic regression

When is survival analysis used?

when the research question is WHEN something will occur… not IF

Survival Analysis is used a lot in what setting in medicine? FYI

cancer treatments

In logistic regression, the coefficients are hard to interpret, so instead what do we look at?

odds ratio

What are the 3 components of a survival analysis?

1. Kaplan-Meier Method/Curve

2. A Cox Proportional Hazard Ratio

3. log-rank test that produces a p-value

The Kaplan-Meier method and cox proportional hazard ratio all MUST account for the possibility of what?

censoring

What does censoring/ censored data mean in this context?

This occurs when the time to event occurrence is not precisely known for individuals

• BASICALLY: lack of data

• Ex: If a patient drops out of a study, we don’t know what happened to them? did they die? survive? etc.

The Kaplan-Meier Method summarizes what?

the probability of survival over time estimated from a sample

How is hypothesis testing done in the Kaplan-Meier Method?

logrank test

What is a hazard?

risk of event occurrence at time t

A hazard function is hazard for an event over _______.

time

This is the equation for a hazard function. What would I do to that equation to create the cox proportional hazards regression model?

Just take the natural log (ln)!!!

In Cox Proportional Hazards Regression Model, what happens is B>0?

an increase in the predictor leads to an increase in the hazard (or decrease in survival)

• Ex: cigarettes smoked a day. If I INCREASE the predictor (# of cigarettes), that leads to an increase in hazard (lung cancer)

In Cox Proportional Hazards Regression Model, what happens is B<0?

an increase in the predictor leads to an decrease in the hazard (or increase in survival)

• Ex: exercise