Turn on suggestions

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

- Home
- /
- Analytics
- /
- Stat Procs
- /
- Test for coincidence??

Options

- RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Mute
- Printer Friendly Page

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

Posted 10-10-2018 07:47 PM
(2494 views)

Hello,

I am performing a multi-linear regression analysis with 1 dichotomous and 1 continuous regressor and there is a significant interaction.

How can I assess coincidence from the PROC REG procedure in SAS?

I have read that ANCOVA is the appropriate method but what if I am only given the ANOVA and parameter estimates output?

Here is my current thought process: if I fit the model for each value of the dichotomous variable then the lines will differ and hence, are not coincident. Am I thinking about this correctly?

5 REPLIES 5

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

What’s your definition of coincidence in this contex?

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

When two lines lie directly on top of eachother

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

If interaction is significant then ANCOVA is not appropriate. Significant interaction means that the two lines do not have the same slope. They may cross at some point but will diverge as you move away from that point. So they definitively don't coincide.

PG

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

I moved your question to the Statistical Procedures community.

- Mark as New
- Bookmark
- Subscribe
- Mute
- RSS Feed
- Permalink
- Report Inappropriate Content

@iressa1313 wrote:1. I am performing a multi-linear regression analysis with 1 dichotomous and 1 continuous regressor and there is a significant interaction.

2. How can I assess coincidence from the PROC REG procedure in SAS?

3. I have read that ANCOVA is the appropriate method but what if I am only given the ANOVA and parameter estimates output?

4. Here is my current thought process: if I fit the model for each value of the dichotomous variable then the lines will differ and hence, are not coincident. Am I thinking about this correctly?

I think there are some issues that need to be clarified:

1. If you have a dichotomous regressor, you want to use PROC GLM with a CLASS statement, not PROC REG.

2. When you fit a model with PROC GLM, you can test whether the interaction term is significant. You can also test whether the coefficient for the dichotomous parameter is significant.

3. I am confused by this question. You say "what if I am only given the ANOVA and parameter estimates output." Do you have the data or not? If you only have the parameter estimates (as a table), then please post it.

4. I would fit a model that includes a CLASS variable (the dichotomous regressor) rather than fit two models, especially if you think there is interaction. To understand the difference between using a CLASS statement and fitting two different models, study the article "The difference between CLASS statements and BY statements in SAS"

Are you ready for the spotlight? We're accepting content ideas for **SAS Innovate 2025** to be held May 6-9 in Orlando, FL. The call is **open **until September 25. Read more here about **why** you should contribute and **what is in it** for you!

What is ANOVA?

ANOVA, or Analysis Of Variance, is used to compare the averages or means of two or more populations to better understand how they differ. Watch this tutorial for more.

Find more tutorials on the SAS Users YouTube channel.