Assignment 4: Moderators

1.- Research question:

On my first assignment, where we had to run an ANOVA Test  I wanted to demonstrate that people who live with a partned have a statistically higher body weight than thos who lived alone.

Now, I am going to introduce a moderator into the equation; Gender. I want to know if the relation is different for men and for women.

2.- Code used:

LIBNAME mydata "/courses/d1406ae5ba27fe300 " access=readonly;
DATA new; set mydata.nesarc_pds;

PROC SORT; BY SEX;

PROC ANOVA; CLASS SPOUSE;
MODEL WEIGHT=SPOUSE;
MEANS SPOUSE;BY SEX;


RUN;

3.- Results:

Procedimiento ANOVA

SEX=1

Información de nivel de clase
Clase	Niveles	Valores
SPOUSE	2	1 2

Número de observaciones leídas	18518
Número de observaciones usadas	18518

---

Procedimiento ANOVA

Variable dependiente: WEIGHT

SEX=1

Fuente	DF	Suma de cuadrados	Cuadrado de la media	F-Valor	Pr > F
Modelo	1	17586689181	17586689181	1325.30	<.0001
Error	18516	245706824924	13269973.262
Total corregido	18517	263293514104

R-cuadrado	Coef Var	Raíz MSE	WEIGHT Media
0.066795	67.71799	3642.797	5379.365

Fuente	DF	Anova SS	Cuadrado de la media	F-Valor	Pr > F
SPOUSE	1	17586689181	17586689181	1325.30	<.0001

---

Procedimiento ANOVA

SEX=1

Nivel de SPOUSE	N	WEIGHT
		Media	Dev std
1	9440	6335.02602	3751.07691
2	9078	4385.59444	3526.67543

---

Procedimiento ANOVA

SEX=2

Información de nivel de clase
Clase	Niveles	Valores
SPOUSE	2	1 2

Número de observaciones leídas	24575
Número de observaciones usadas	24575

---

Procedimiento ANOVA

Variable dependiente: WEIGHT

SEX=2

Fuente	DF	Suma de cuadrados	Cuadrado de la media	F-Valor	Pr > F
Modelo	1	30250318951	30250318951	3381.65	<.0001
Error	24573	219816354481	8945442.3343
Total corregido	24574	250066673433

R-cuadrado	Coef Var	Raíz MSE	WEIGHT Media
0.120969	67.89023	2990.893	4405.484

Fuente	DF	Anova SS	Cuadrado de la media	F-Valor	Pr > F
SPOUSE	1	30250318951	30250318951	3381.65	<.0001

---

Procedimiento ANOVA

SEX=2

Nivel de SPOUSE	N	WEIGHT
		Media	Dev std
1	10370	5704.00630	3301.22494
2	14205	3457.53050	2742.26209

4.- Interpretation:

What SAS tells us is that the relation between living with a partner (Spouse =1) o living without it (Spouse=2)  and the average body weight is statistically sigificant both for men (sex=1) and for women (sex=2). Furthermore, in both cases the relation works in the same direction and with a similar intensity. Thus we can conclude that sex is not a good moderator in this relation.