×

### Let's log you in.

or

Don't have a StudySoup account? Create one here!

×

or

21

0

2

# Class Note for SW 983 with Professor McDonald at KU

Marketplace > Kansas > Class Note for SW 983 with Professor McDonald at KU

No professor available

These notes were just uploaded, and will be ready to view shortly.

Either way, we'll remind you when they're ready :)

Get a free preview of these Notes, just enter your email below.

×
Unlock Preview

COURSE
PROF.
No professor available
TYPE
Class Notes
PAGES
2
WORDS
KARMA
25 ?

## Popular in Department

This 2 page Class Notes was uploaded by an elite notetaker on Friday February 6, 2015. The Class Notes belongs to a course at Kansas taught by a professor in Fall. Since its upload, it has received 21 views.

×

## Reviews for Class Note for SW 983 with Professor McDonald at KU

×

×

### What is Karma?

#### You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 02/06/15
SW983 CODING OF CATEGORICAL VARIABLES IN MULTIPLE REGRESSION ANALYSIS Overview Multiple regression analysis MR and other correlation based statistical techniques like factor analysis are typically used for continuous variables It was developed as an extension of correlation partial and semi partial The techniques discussed today broaden its application to include the use of categorical variables The goal then is to learn how categorical variables can be introduced to MR analysis and how the results can be interpreted Recall that categorical variables can be used to measure group membership Subjects differ from each other in type or kind rather than in degree continuous The categorical or discrete variable may re ect assignment to a group eg experimental or control group or some attribute variable e g sex of respondent Note Methods for coding categorical variables are the same regardless of whether the data are experimental or nonexperimental explanatoy or predictive Codi g Coding of categorical variables is not simply a statistical or mathematical or clerical function but depends upon the validity of underlying conceptualizations to be useful eg treatment vs control It is important to remember that what we are doing throughout this chapter is comparing means across groups just as we did using ttests and AN OVA The overall results will always be the same regardless of the coding method used dummy effect and orthogonal and these results will be identical to ttest or ANOVA when more than two groups are involved Dummy Coding 1 most common Definition Use of zero39s and one s to denote group membership called indicator coding in our text 0 not a member of group 1 member of group Rule Number of dummy variables needed k Number of groups g l Dummy coding allows multiple regression to be used to compare group means ie metric dependent variable and two groups Results will be identical to ttests in the case of just two groups or oneway ANOVA in the case of more than two groups Consider the equation Y b0 Z kak k Where Y39predicted value for any individual mean for the group b0 mean for the omitted group bk difference in mean for represented group and omitted group T k F 0 Xk 1 if member of kth group other wise 0 SSreg SSbetween groups SSresidual SSwithin groups R2 Eta2 ANOVA F t2 two groups F ANOVA more than two groups b0 intercept mean for omitted group b1 difference between group 1 and omitted group b2 difference between group 2 and omitted group etc t ratio statistic for each b coefficient is a test of the signi cance of the difference between means of the omitted group and the group represented by the particular dummy variable associated with b Note that this is not available from oneway unless you run contrasts Effect Coding Fixed Effects Linear Model Definition Like dummy coding except that the omitted group is assigned l39s rather than 0 s in all the vectors ie group variables Remember overall results will not differ with effect or dummy coding However interpretation of the regression coefficients is very different Regression coefficients not re ect the effects of treatments ie deviations from the grand mean b0 F bk deviation of mean for group i from grand mean Y39 mean for the group To calculate the b for the omitted group remember that Z bg 0

×

×

### BOOM! Enjoy Your Free Notes!

×

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

## Why people love StudySoup

Jim McGreen Ohio University

#### "Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Kyle Maynard Purdue

#### "When you're taking detailed notes and trying to help everyone else out in the class, it really helps you learn and understand the material...plus I made \$280 on my first study guide!"

Steve Martinelli UC Los Angeles

#### "There's no way I would have passed my Organic Chemistry class this semester without the notes and study guides I got from StudySoup."

Parker Thompson 500 Startups

#### "It's a great way for students to improve their educational experience and it seemed like a product that everybody wants, so all the people participating are winning."

Become an Elite Notetaker and start selling your notes online!
×

### Refund Policy

#### STUDYSOUP CANCELLATION POLICY

All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email support@studysoup.com

#### STUDYSOUP REFUND POLICY

StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here: support@studysoup.com

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to support@studysoup.com