# Parametric Statistical homework help

## Parametric Statistical Inference/Modelling

1. Create box plots for both X and Y.  Are there any outliers

2 Make a Scatter plot with Regression.  Does there appear to be a linear relationship?  What two points appear to be potential outliers?

3. Check for outliers using the semi-studentized method.  Are there any outliers?  What are the absolute values of the semi-studentized residuals you identified in question 2?

4.  Do a check of normality by using a probability plot of the residuals.        Include:

a.   The null and alternative hypotheses,

b.   The p-value of the test,

c.   Your decision based on a 0.05 level of significance, and

d.   Minitab copy of your plot.

5   Do a check of equal variances by performing a Modified Levene Test. Include:

a.    The null and alternative hypotheses,

b.    The p-value of the test,

c.    Your decision based on a 0.05 level of significance, and

d.    Minitab copy of your plot.

6   Perform a Lack of Fit Test to check if linear regression function is appropriate.  Include:

a.   The null and alternative hypotheses,

b.   The correct F-statistic and p-value of the test,

c.   Your decision based on a 0.05 level of significance, and

d. Minitab copy of your ANOVA output.

7.   Even though you may not have found any assumption violations perform a Box-Cox analysis on Y to see if any transformation is suggested.  Include the

a.   Estimated and rounded lambda values,

b.   The interpretation of this value, and

c.   The Box-Cox plot.

NOTE: This can only be done using Minitab Version 15 or higher – i.e. student version 14 does not contain Box-Cox program.

8. Find Bonferroni joint confidence intervals for Bo and B1 with a 90% family confidence level and include your interpretation of these intervals.  You can use the Minitab output to find s{bo} and s{b1}

9.    Use Minitab to find Bonferroni simultaneous confidence intervals for new X observations of and 10 using a 95% family confidence level.  Include your the output and interpretation of these intervals.

9.1   Follow-up question 1: What is the interpretation of the level of confidence for the confidence intervals in the output?

9.2    Follow-up question 2: Can you think of a reason why these new X values might not be reliable?

9.3     Follow-up question 3: Show mathematically how one would use the Minitab output to get the simultaneous level of confidence for new observations.