Chi-Square Distribution Question

[Algo_Design_Kid]

First question : Why is the peak of the distribution always just a bit before the actual dF?

This can be seen here..

Second : Why when dF = 2 does the left side of the curve just go straight up the y axis and never find its way to 0?

The teacher is totally puzzled in class and I can't find anything written in plain english that tells me why.


Thanks

 

[FGBL07]

You are misreading the graph for dF=2.

Take a look at the density function: for dF=2 the function collapses to 0.5*e**(-x/2). The result for x=0 is 0.5.

 

[Algo_Design_Kid]

Quote from FGBL07:

You are misreading the graph for dF=2.

Take a look at the density function: for dF=2 the function collapses to 0.5*e**(-x/2). The result for x=0 is 0.5.

Seems you are right Chi Sq Pdf x= 0 is .5

Can you actually explain what this means? Neither my teacher or book are helping.. I am probably missing something simple.