What does PROC REG do in SAS?
Proc REG Statement names the SAS data set to be used by PROC REG. If DATA= is not specified, REG uses the most recently created SAS data set. OUTEST=SASdataset. requests that parameter estimates be output to this data set.
How do you read Studentized residuals?
A studentized residual is calculated by dividing the residual by an estimate of its standard deviation. The standard deviation for each residual is computed with the observation excluded. For this reason, studentized residuals are sometimes referred to as externally studentized residuals.
What is a studentized residual used for?
In statistics, a studentized residual is the quotient resulting from the division of a residual by an estimate of its standard deviation. It is a form of a Student’s t-statistic, with the estimate of error varying between points. This is an important technique in the detection of outliers.
What does residuals vs fitted plot show?
The residuals vs fit plot is commonly used to detect non-linearity, unequal error variances and outliers. When a linear regression model is suitable for a data set, then the residuals are more or less randomly distributed around the 0 line.
How do you find the prediction interval?
In addition to the quantile function, the prediction interval for any standard score can be calculated by (1 − (1 − Φµ,σ2(standard score))·2). For example, a standard score of x = 1.96 gives Φµ,σ2(1.96) = 0.9750 corresponding to a prediction interval of (1 − (1 − 0.9750)·2) = 0.9500 = 95%.
What is a good studentized residuals?
Three of the studentized residuals — –1.7431, 0.1217, and, 1.6361 — are all reasonable values for this distribution. But, the studentized residual for the fourth (red) data point (–19.799) sticks out like a very sore thumb.
What are studentized residuals used for?
The good thing about internally studentized residuals is that they quantify how large the residuals are in standard deviation units, and therefore can be easily used to identify outliers: An observation with an internally studentized residual that is larger than 3 (in absolute value) is generally deemed an outlier.