ASA Connect

Before running your regression model, write out your regression equation.

I.E., Y=B0 +B1*Housing etc.

 Each Bi indicates the effect of a unit increase in Xi, with all other X's held constant.

Also, if you have 0,1,2 coding, I would set variables for 1 versus 0 and 2 versus 0.  By using the 0,1,2 coding, your model includes the assumption that a unit increase is the same from 0 to 1 as from 1 to 2.  I suggest testing that assumption.

Hope this helps you to get started.

------------------------------

Brandy Sinco
Research Associate
------------------------------


Original Message:
Sent: 04-25-2015 12:27
From: Silas Hyzer
Subject: Multiple linear regression help

This message has been cross posted to the following eGroups: Social Statistics Section and ASA Connect .
-------------------------------------------
Hello all

I am doing a multiple linear regression for a final capstone project for my MPH. I am having issues with running my regression.

Here is what's up:

I am using SPSS

My DV (which is HIV viral load) is continuous (but I also have it coded as categorical-undetectable, low and high- which I would rather use as a multinomial regression).

All of my IV's are categorical and qualitative (but coded as 0,1,2) all but one is a binary category (yes-1, no-0) only one IV has 3 options (it is housing- 1-permanent housing, 2-temp housing and 3-homeless)

I can do a simple regression with my DV and a single IV (which is housing, with permanent housing set as my reference category). Beyond that, every time I put in other variables it doesn't give a P value for all of my IVs (some it just shows a period) and I dont know how to interpret them-like one of my IV's is "Has history of mental health diagnosis" and it is a yes/no variable-so when it spits out a P value for the variable, how do I know if that means yes or no is the p value significance?

I do have a small n=101

Any help is appreciated! Thanks everyone

Silas

------------------------------
Silas Hyzer
------------------------------

Brandy,

In general, in a multiple regression, "with all other X's held constant" is not the correct interpretation.  Each Bi summarizes the change in Y per unit change in Xi after adjusting for simultaneous linear change in the other X's in the data at hand.

The data may support predictions in which the other X's are held constant, but that is a different purpose of regression.  When we interpret a regression coefficient, we are usually making a statement about the size of an effect.

Many textbooks give the held-constant interpretation, but straightforward mathematics shows that that is not how multiple regression works.

------------------------------
David Hoaglin
------------------------------


Original Message:
Sent: 04-27-2015 10:16
From: Brandy Sinco
Subject: Multiple linear regression help

Before running your regression model, write out your regression equation.

I.E., Y=B0 +B1*Housing etc.

 Each Bi indicates the effect of a unit increase in Xi, with all other X's held constant.

Also, if you have 0,1,2 coding, I would set variables for 1 versus 0 and 2 versus 0.  By using the 0,1,2 coding, your model includes the assumption that a unit increase is the same from 0 to 1 as from 1 to 2.  I suggest testing that assumption.

Hope this helps you to get started.

------------------------------

Brandy Sinco
Research Associate
------------------------------


Original Message:
Sent: 04-25-2015 12:27
From: Silas Hyzer
Subject: Multiple linear regression help

This message has been cross posted to the following eGroups: Social Statistics Section and ASA Connect .
-------------------------------------------
Hello all

I am doing a multiple linear regression for a final capstone project for my MPH. I am having issues with running my regression.

Here is what's up:

I am using SPSS

My DV (which is HIV viral load) is continuous (but I also have it coded as categorical-undetectable, low and high- which I would rather use as a multinomial regression).

All of my IV's are categorical and qualitative (but coded as 0,1,2) all but one is a binary category (yes-1, no-0) only one IV has 3 options (it is housing- 1-permanent housing, 2-temp housing and 3-homeless)

I can do a simple regression with my DV and a single IV (which is housing, with permanent housing set as my reference category). Beyond that, every time I put in other variables it doesn't give a P value for all of my IVs (some it just shows a period) and I dont know how to interpret them-like one of my IV's is "Has history of mental health diagnosis" and it is a yes/no variable-so when it spits out a P value for the variable, how do I know if that means yes or no is the p value significance?

I do have a small n=101

Any help is appreciated! Thanks everyone

Silas

------------------------------
Silas Hyzer
------------------------------

Before running your regression model, write out your regression equation.

I.E., Y=B0 +B1*Housing etc.

 Each Bi indicates the effect of a unit increase in Xi, with all other X's held constant.

Also, if you have 0,1,2 coding, I would set variables for 1 versus 0 and 2 versus 0.  By using the 0,1,2 coding, your model includes the assumption that a unit increase is the same from 0 to 1 as from 1 to 2.  I suggest testing that assumption.

Hope this helps you to get started.

------------------------------

Brandy Sinco
Research Associate
------------------------------


Original Message:
Sent: 04-25-2015 12:27
From: Silas Hyzer
Subject: Multiple linear regression help

This message has been cross posted to the following eGroups: Social Statistics Section and ASA Connect .
-------------------------------------------
Hello all

I am doing a multiple linear regression for a final capstone project for my MPH. I am having issues with running my regression.

Here is what's up:

I am using SPSS

My DV (which is HIV viral load) is continuous (but I also have it coded as categorical-undetectable, low and high- which I would rather use as a multinomial regression).

All of my IV's are categorical and qualitative (but coded as 0,1,2) all but one is a binary category (yes-1, no-0) only one IV has 3 options (it is housing- 1-permanent housing, 2-temp housing and 3-homeless)

I can do a simple regression with my DV and a single IV (which is housing, with permanent housing set as my reference category). Beyond that, every time I put in other variables it doesn't give a P value for all of my IVs (some it just shows a period) and I dont know how to interpret them-like one of my IV's is "Has history of mental health diagnosis" and it is a yes/no variable-so when it spits out a P value for the variable, how do I know if that means yes or no is the p value significance?

I do have a small n=101

Any help is appreciated! Thanks everyone

Silas

------------------------------
Silas Hyzer
------------------------------

Turning your three-valued predictor into two dummy variables each coded 0 or 1 is the better approach because it avoids making the assumption of equal distance between the categories. David Greenberg,Sociology Department, New York University

------------------------------
David Greenberg
Professor
New York University
------------------------------


Original Message:
Sent: 04-27-2015 10:16
From: Brandy Sinco
Subject: Multiple linear regression help

Before running your regression model, write out your regression equation.

I.E., Y=B0 +B1*Housing etc.

 Each Bi indicates the effect of a unit increase in Xi, with all other X's held constant.

Also, if you have 0,1,2 coding, I would set variables for 1 versus 0 and 2 versus 0.  By using the 0,1,2 coding, your model includes the assumption that a unit increase is the same from 0 to 1 as from 1 to 2.  I suggest testing that assumption.

Hope this helps you to get started.

------------------------------

Brandy Sinco
Research Associate
------------------------------


Original Message:
Sent: 04-25-2015 12:27
From: Silas Hyzer
Subject: Multiple linear regression help

This message has been cross posted to the following eGroups: Social Statistics Section and ASA Connect .
-------------------------------------------
Hello all

I am doing a multiple linear regression for a final capstone project for my MPH. I am having issues with running my regression.

Here is what's up:

I am using SPSS

My DV (which is HIV viral load) is continuous (but I also have it coded as categorical-undetectable, low and high- which I would rather use as a multinomial regression).

All of my IV's are categorical and qualitative (but coded as 0,1,2) all but one is a binary category (yes-1, no-0) only one IV has 3 options (it is housing- 1-permanent housing, 2-temp housing and 3-homeless)

I can do a simple regression with my DV and a single IV (which is housing, with permanent housing set as my reference category). Beyond that, every time I put in other variables it doesn't give a P value for all of my IVs (some it just shows a period) and I dont know how to interpret them-like one of my IV's is "Has history of mental health diagnosis" and it is a yes/no variable-so when it spits out a P value for the variable, how do I know if that means yes or no is the p value significance?

I do have a small n=101

Any help is appreciated! Thanks everyone

Silas

------------------------------
Silas Hyzer
------------------------------

Turning your three-valued predictor into two dummy variables each coded 0 or 1 is the better approach because it avoids making the assumption of equal distance between the categories. David Greenberg,Sociology Department, New York University

------------------------------
David Greenberg
Professor
New York University
------------------------------


Original Message:
Sent: 04-27-2015 10:16
From: Brandy Sinco
Subject: Multiple linear regression help

Before running your regression model, write out your regression equation.

I.E., Y=B0 +B1*Housing etc.

 Each Bi indicates the effect of a unit increase in Xi, with all other X's held constant.

Also, if you have 0,1,2 coding, I would set variables for 1 versus 0 and 2 versus 0.  By using the 0,1,2 coding, your model includes the assumption that a unit increase is the same from 0 to 1 as from 1 to 2.  I suggest testing that assumption.

Hope this helps you to get started.

------------------------------

Brandy Sinco
Research Associate
------------------------------


Original Message:
Sent: 04-25-2015 12:27
From: Silas Hyzer
Subject: Multiple linear regression help

This message has been cross posted to the following eGroups: Social Statistics Section and ASA Connect .
-------------------------------------------
Hello all

I am doing a multiple linear regression for a final capstone project for my MPH. I am having issues with running my regression.

Here is what's up:

I am using SPSS

My DV (which is HIV viral load) is continuous (but I also have it coded as categorical-undetectable, low and high- which I would rather use as a multinomial regression).

All of my IV's are categorical and qualitative (but coded as 0,1,2) all but one is a binary category (yes-1, no-0) only one IV has 3 options (it is housing- 1-permanent housing, 2-temp housing and 3-homeless)

I can do a simple regression with my DV and a single IV (which is housing, with permanent housing set as my reference category). Beyond that, every time I put in other variables it doesn't give a P value for all of my IVs (some it just shows a period) and I dont know how to interpret them-like one of my IV's is "Has history of mental health diagnosis" and it is a yes/no variable-so when it spits out a P value for the variable, how do I know if that means yes or no is the p value significance?

I do have a small n=101

Any help is appreciated! Thanks everyone

Silas

------------------------------
Silas Hyzer
------------------------------