Need Urgent Help - Why multiple and Simple Regression Out Puts Different

#1
Hi

Im a new comer to statistics, im using SPSS, my dependent variable is Purchase Intention and Independent variable is Security..why the Sig. value is different in these two out puts? When doing individually which means simple it gives .000 but doing multiple it gives .750?



 

hlsmith

Omega Contributor
#2
So does this output show first a saturated model where you put everything in and secondly, a model with just Security?


Can you tell us about how these variables are formatted (continouos/categorical)?


The first model controls for all variables. So each variable carves out its own uniques explanatory piece of the pie, but they may have a little overlap with the other variables. So think about the variance in the dependent variable as a Venn graph. So when Security is all by itself, it is a two orb Venn graph. Next, when you add the other variables you can see there now is some explanatory competition amongst them.
 
#3
So does this output show first a saturated model where you put everything in and secondly, a model with just Security?


Can you tell us about how these variables are formatted (continouos/categorical)?


The first model controls for all variables. So each variable carves out its own uniques explanatory piece of the pie, but they may have a little overlap with the other variables. So think about the variance in the dependent variable as a Venn graph. So when Security is all by itself, it is a two orb Venn graph. Next, when you add the other variables you can see there now is some explanatory competition amongst them.
yes, the first picture is with all variables...multiple regression, second picture is just dependent variable and security (inexpedient variable)

these data got from a likert scale questionnaire, i believe that is categorical data?

so i can just explain as a whole in the first picture right? and when its taking as single variable, security does have a relation with the purchase intention...so is it normal that those Sig. values changing when its analyzing as a group and individually right?