What I learned it that firstly use Best Subsets Approach as a screening tool, then the stepwise selection procedures can help you finally decide which models might be best subset models (at this time the number of those models is pretty small to handle). If one of the models meets the model conditions, does a good job of summarizing the trend in the data, and most importantly allows you to answer your research question, then congrats your job is done.

Computing best subset of predictors for linear regression
I am writing a very simple HTML code which is listed below. Written in notepad and opening in IE-8 and Firefox (OS: Window Vista).

&lt;html&gt;
&lt;body&gt;
    &lt;table border="1"&gt;&lt;tr&gt;&lt;td&gt;test&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
&lt;/body&gt;
&lt;/html&gt;


There is nothing special in the above code, It is creating some space from top left corner.



Which can be easily removed by using the following code

&lt;body style="margin:0; padding:0"&gt;


Now i have find out the default margin and padding, which is 4 for Firefox and different for IE-8. 

&lt;body style="margin:4; padding:4"&gt;


I have some question on this scenario.


Why this value is 4?
From where this value is coming, is it saved somewhere?
Can we modify (configurable) this default value?
How these values are different for browsers? 


Thanks.
