Compute the internally-studentized residuals corresponding to each chimpanzee. 2. Which chimpanzee has the largest (positive or negative) internally-studentized residual and which chimpanzee has the internally-studentized residual closest to 0? Since the distribution of internally-studentized residuals is not ‘pretty’, is it easy to judge how large the outlier must be to be significant?
You are a researcher conducting research about chimpanzees’ cognitive processes. You have just spent a year of your life becoming familiar with the 5 new chimpanzees you purchased with your new grant money. Your first task for the first year was to make sure that all the chimpanzees behave the same way and none of them is either ‘too smart or too dumb’ of an outlier. The experiment you most recently worked on was finished and all you had to do was to analyze the data and see whether any new chimpanzee is an outlier. In your last experiment you were trying to see whether there is a relationship between the number of hours learning a task (continuous variable) and the task performance (scored using a continuous score between 0 and 15). Each chimpanzee was learning the task for a different number of hours and then each chimpanzee performed the task and its performance got scored. Yesterday, you ran a simple regression with intercept to see whether the number of learning hours can predict the chimpanzee’s task score. Until last night, your life was going according to plan.
However, today everything has changed. There was a fire in your office and most of your important research data was lost. Luckily, the chimpanzees are ok. You are rummaging in tears through the ashes in your office and suddenly your face brightens. You have just found a part of an SAS output you ran last night. Granted, it is charred a bit on the edges, but all the important results are there. Now you know that you can finish your research investigating whether any chimpanzee is a significant outlier and then go on with your grant.
This is what you found:
|
Observations |
residuals |
hii (aka leverage) |
|
Chimpanzee Adam |
0 |
0.5439 |
|
Chimpanzee Bob |
1 |
0.3421 |
|
Chimpanzee Cecile |
1 |
0.2018 |
|
Chimpanzee David |
-4 |
0.2632 |
|
Chimpanzee Eve |
2 |
0.6491 |
- Compute the internally-studentized residuals corresponding to each chimpanzee.
2. Which chimpanzee has the largest (positive or negative) internally-studentized residual and which chimpanzee has the internally-studentized residual closest to 0? Since the distribution of internally-studentized residuals is not ‘pretty’, is it easy to judge how large the outlier must be to be significant?
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