Final answer:
An outlier is the term used for a point outside the lower control limit on an r-chart, which indicates a deviation from the other data points and suggests the potential need for process control adjustments.
Step-by-step explanation:
The term used for a point which is outside of the lower control limit on an r-chart is known as an outlier. In the context of regression analysis, an outlier is a data point that is significantly different from other data points in the data set. It deviates so much from other observations as to arouse suspicion that it was generated by a different mechanism. In statistics, outliers can be identified in various ways, one common method being if a data point is more than two standard deviations away from the best-fit line or the expected value. Outliers can have large errors, and in the context of control charts, such as r-charts, they indicate that the process may be out of control and require investigation.
On graphing calculators like the TI-83 or 84, outliers can be visually identified by plotting the data and checking if any points lie beyond lines that represent two standard deviations from the line of best fit. It is important to examine these outliers as they can potentially be influential points that significantly affect the slope of the regression line and the overall correlation among the variables in a data set