ANOVA Flashcards
What are type 1 and type 2 probability errors?
A type-1 error (false-positive) occurs when an investigator rejects a null hypothesis that is actually true in the population.
A type-2 error (false-negative) occurs when an investigator fails to reject a null hypothesis that is actually false in the population.
What is the p statistic?
The p-value is the probability of observing results at least as extreme as observed from the statistical test if the null hypothesis is true
What is Randomised Complete Block Design?
Blocks are included to reduce error variation. We include a blocking variable that we hope will reduce error variation
What considerations should an investigator remember when choosing a blocking variable?
Since choosing a block loses degrees of freedom, we need to choose a worthwhile variable:
- the blocks should differ as much as possible (big between block variation)
- little within block variation (consistency within blocks)
- the main purpose of blocking is to reduce error variance.
- Each treatment appears exactly once in each block
What are the requirements for a valid ANOVA?
Independent samples from a normal population with the same variance.
What is Correlation analysis and Regression analysis?
Correlation analysis measures the strength and direction of the linear relationship between two variables.
Regression analysis estimates the value of a dependant variable based on the value of at least one independent variable.
What are the linear regression assumptions?
We assume the data are linearly related (can be described by a line) and that all deviations from the line (errors) are independent, normally distributed, and with mean 0 and constant variance.
What are residuals and why are they important?
A residual is the difference between the observed value and the mean value that the model predicts for the observation. They are useful because they indicate the extent to which the model explains the variation in the observed data
Interpret the regression equation in terms of the meanings of the coefficients.
B* is the intercept and it is the estimated value when the value of X is 0.
B` is the slope coefficient and it measures the estimated change in the average value of Y for a one-unit change in X.
What is the Residual Standard Error?
It is an estimate of the average amount that the response will deviate from the true regression line.
What is the standard error of the regression slope coefficient?
Residual Standard Error divided by the Regression Slope coefficient.
