**PUAD 628 Homework 3**

**(Practicum for Final exam)**

DUE: April 15^{th} , 5: 00 pm

**Name_________________________________**

- Students

are allowed to share*ideas*on

Homework 3. However, you have to write the homework independently in

your own words. Also it is prohibited to share the homework files with others. Any

violation to this requirement will be considered as violation of the Academic

Honor Code of UB. - You

are allowed to use your class materials (e.g., classnotes, textbooks, quizzes, Mid-term

exam, Homework 1, or preexisting materials shown in open-resources, etc.). - Type your answers in a different color with relevant

explanations. Copy and paste only essential parts of SPSS output for

your answers. Unnecessary information of output will be the target for a

partial credit or non-credit. When you paste a table, use “Paste Special”

command under “Edit” menu on MS Word. Then choose to paste as a “Picture”. - Use

the SPSS data file, NELS_school_mid.sav and examine the data file. You can

download from the course web site. Go to “Sakai” to download the file.

- Create

a histogram for the “g10urban” variable. Change the number of classes (intervals)

to 12, while keeping other specifications as automatically specified by SPSS. Copy

and paste the resulting histogram into your assignment

*Hint. *

a histogram, place your cursor in the plot and then click the plot. Right click

with Properties, Click Binning. Mark Custom, Set # of Intervals as 12

- Do

you think if it is appropriate to generate a histogram using on a categorical

variable that includes three categories or groups? Why or why not?

- Create

a bar graph for the “g10urban”. Choose “% of cases” for the “Bars

Represent” part of the dialog box on SPSS. Move the variable into “Category

Axis”. Copy and paste the bar graph into your assignment. Please answer the

following questions.

a. Why is a bar

graph an appropriate display in this case, rather than a histogram?

b. Are there

more URBANs than SUBURBAN’s in this data set?

c. What

percentage in this data set is SUBURBAN?

d. Would a pie

chart be appropriate to depict these data? Why or why not? Create one and copy

and paste it into your assignment to show me that you know how to do it.

T

/ F

- LECTURE 7-1 and 7-2 show residual

assumptions clearly. Specify any assumptions for**the errors**or**residuals**.

* Hint: If you express the answer using symbols, please be accurate in the notation and use MS Word menu: Insert- Symbol (e.g., Greek letter or alphabetical letter? Subscript or superscript or regular?)*

- How do

you check whether or not the independence assumption is violated? Is there any

way to check the violation of the independence assumption using a statistical

test (e.g., p value)?

- How do

you check whether or not the normality assumption is violated in the residuals?

Refer to Homework 2 or Mid-Term Exam when write down your answer.

- How do you check whether or not the

homoscedastisity (= equal variance) assumption is violated in the residuals?

Refer to Homework 2 or Mid-Term Exam.

- (True/False)

If the assumption of linearity between X and Y is not satisfied according to a

scatterplot, we cannot use the correlation index shown in the correlation table

because the result would be biased.

T or F

- SPSS generates three tables as parts of the

output when you run a regression (e.g., Model Summary, ANOVA, and Coefficients).

We interpret (1) Overall test for our model and (2) Individual slope tests for

slope coefficients, respectively. We will have the same results in the two

tests (i.e., overall test and individual slope test) in Simple regression.

However, the results of the two tests ((i.e., overall test and slope tests) are

not necessarily identical in Multiple regression because multiple regression

includes 2 different independent variables. Please indicate the title of

SPSS Table for the two different tests (i.e., overall test and individual

slope tests) and the name of each test, respectively. Fill in the table.

Overall test for model | Individual slope tests | |

SPSS Table Title | ||

Test name |

- We will use (k-1) dummy variables to

represent k groups. T or F

**Please save your homework using a title “lastname.firstname.PUAD628homework3.docx”. To follow the instruction is important. Thank you.**

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April 22, 2019

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