homework

Stat 210B: Homework Assignment 2

Due: Friday January 31

An experiment was performed to reduce the number of off-grade tiles produced.
The experiment studied seven factors with levels:

A: lime additive content (1%, 5%);
B: additive granularity (coarse, fine);
C: agalmatolite content (43%, 53%);
D: agalmatolite type (current, cheaper);
E: charge quantity (1200kg, 1300kg);
F: waste return quantity (0%, 4%);
G: felspar content (0%, 5%).

The response was the number of off-grade tiles out of a sample of 100.
The design matrix and response data are given below (data)

A B C D E F G count 1 - - - - - - - 16 2 - - - + + + + 17 3 - + + - - + + 12 4 - + + + + - - 6 5 + - + - + - + 6 6 + - + + - + - 68 7 + + - - + + - 42 8 + + - + - - + 26

Analyze the experimental data using a logistic regression model. Report your final model and explain how you reach the final model.
Recommend the optimum level settings to reduce the number of off-grade tiles. Predict the outcome for the optimum level settings. Give a confidence interval for your prediction.

* Print necessary outputs only and summarize the result.

Hongquan Xu <hqxu@stat.ucla.edu>