# Fit the regression model of Y (change in refraction error) on X1, sex and X1*sex. Write down the fitted regression model.

• Description of the data set is provided in page 161 (problem 12 in chapter 8). Dataset “EX0812.txt” is posted.

(Note: If you use infile and input statement to read in data, put “\$” after the variable sex to indicate that the values are characters. E.g.

input id x1 x2 y clrzne sex \$ 😉

• Fit the regression model of Y (change in refraction error) on X1, sex and X1*sex. Write down the fitted regression model.
• Based on the fitted model in (a), write down the regression models of Y on X1 for males and females separately. What is the difference of intercepts in these two models? What is the difference of slopes in these two models? Which do they correspond to the estimated coefficient in model (a), respectively?
• Test whether the straight lines for males and females coincide (i.e., are the same) with alpha=0.1. State your null hypothesis in terms of the coefficients. Provide you SAS code and output for conducting the analysis. Figure out your F value and p value based on output, and then draw a conclusion.
• Test whether the straight lines for males and females are parallel with alpha=0.1. State your null hypothesis in terms of the coefficients. Provide you SAS code and output for conducting the analysis. Figure out your F value and p value based on output, and then draw a conclusion.
• Based on your answers to questions (c) and (d), comment on differences and similarities in the change in refraction-baseline refractive error relationship for males and females.

## Calculate the price of your order

550 words
We'll send you the first draft for approval by September 11, 2018 at 10:52 AM
Total price:
\$26
The price is based on these factors:
Number of pages
Urgency
Basic features
• Free title page and bibliography
• Unlimited revisions
• Plagiarism-free guarantee
• Money-back guarantee
On-demand options
• Writer’s samples
• Part-by-part delivery
• Overnight delivery
• Copies of used sources
Paper format
• 275 words per page
• 12 pt Arial/Times New Roman
• Double line spacing
• Any citation style (APA, MLA, Chicago/Turabian, Harvard)

# Our guarantees

Delivering a high-quality product at a reasonable price is not enough anymore.
That’s why we have developed 5 beneficial guarantees that will make your experience with our service enjoyable, easy, and safe.

### Money-back guarantee

You have to be 100% sure of the quality of your product to give a money-back guarantee. This describes us perfectly. Make sure that this guarantee is totally transparent.

### Zero-plagiarism guarantee

Each paper is composed from scratch, according to your instructions. It is then checked by our plagiarism-detection software. There is no gap where plagiarism could squeeze in.

### Free-revision policy

Thanks to our free revisions, there is no way for you to be unsatisfied. We will work on your paper until you are completely happy with the result.