Student error message. Possibly Mac-related?

wcraine

One my students keeps getting an error in Notebook 4. She is on a Mac, and was originally using Safari. I encouraged her to download and use Chrome, but the error still persists.

We've tried reconnecting, restarting, running all, running all above, re-running each code box by hand, and it still doesn't work.

She gets the error when she tries to run the provided code to make the polynomial functions of different degrees. She gets this error:

Error in eval(predvars, data, env): object 'default_rate' not found
Traceback:

predict(sat_model_1, newdata = data.frame(SAT_avg = test_dat$SAT_avg))
predict.lm(sat_model_1, newdata = data.frame(SAT_avg = test_dat$SAT_avg))
model.frame(Terms, newdata, na.action = na.action, xlev = object$xlevels)
model.frame.default(Terms, newdata, na.action = na.action, xlev =␣
↪object$xlevels)
eval(predvars, data, env)
eval(predvars, data, env)

In earlier parts of the notebook, she is able to find the correlation, for example, using:
cor(test_dat$default_rate, pred_deg5) ^ 2
so it seems like the program can find and use the variable default_rate.

Any help would be greatlly appreciated by both of us!

Bill

ivonnem10

Hello @wcraine,

I think the first thing I can think of is making sure that the student is correctly setting the variable data in their model such as:
mymodel <- lm(defaultrate ~ poly(.., 2) + …, data = train)

Let me know if this helps.

wcraine

ivonnem10

She couldn't even get that far. The uneditable provided code wouldn't run.

Tomorrow I will have her start fresh. Maybe whatever code broke from using Safari is still in her saved notebook causing trouble, even though she has switched to Chrome.

dylarm

wcraine

This has seemed to come up a few times. Once it was solved by restarting the kernel in the notebook (not sure if you meant that by "restarting," or restarting the computer as a whole). The other times it was solved by either starting fresh (like it seems you plan to), or something unknown (because they haven't replied back 🙃 ).

Edit: I see now that you were one of the people who had the "restart kernel" issue/solution, oops!

dashiell-young-saver

Take a look back at the student's answer for Exercise 1.5 in the same notebook. When they define sat_model_1, it should be using this code: sat_model_1 <- lm(default_rate ~ SAT_avg, data = sample_dat) . If the code is different, this may be causing the problem later in the notebook, as the model will be incorrectly defined.

wcraine

dashiell-young-saver

I hadn't thought of that, but her sat_model_1 was correct.

She started over in Chrome and, although she was less than thrilled to do so, was able to complete the notebook with no additional problems.

It seems like it was a Safari issue that hung around in the saved notebook.

Thanks for your suggestions!