Moving average question

Eric's collar · 19 May 2011 at 17:35

Roger wants to analyse how much customers are spending on stationary each month. He wants to use 12-point moving averages and take it over a 3 year period. How many moving averages will he have over 3 years.

So what's the answer?

The obvious answer would be 36 but that is definitely wrong. I'm think it's 25 but I'm not sure. Can anyone give a definitive answer?

muon · 19 May 2011 at 17:40

n - (k-1) = 25 where n = 36 and k = 12

So 25 degrees of freedom?

I last did stats 4 years ago though.

Eric's collar · 19 May 2011 at 17:43

ghost101 said:
n - (k-1) = 25 where n = 36 and k = 12

So 25 degrees of freedom?

I last did stats 4 years ago though.

No.

muon · 19 May 2011 at 17:49

Eric's collar said:
No.

lol ok. like i said, this was a long time ago.

Eric's collar · 19 May 2011 at 17:53

To work the first moving average you do

(jan+feb+mar+april+may+june+july+aug+sep+oct+nov+dec)/4 then

(feb+mar+april+may+june+july+aug+sep+oct+nov+dec+(jan of next year))/4

and so on...

Aero · 19 May 2011 at 17:53

Sounds suspiciously like homework....

muon · 19 May 2011 at 17:54

Eric's collar said:
To work the first moving average you do

(jan+feb+mar+april+may+june+july+aug+sep+oct+nov+dec)/4 then

(feb+mar+april+may+june+july+aug+sep+oct+nov+dec+(jan of next year))/4

and so on...

I know what a MA process is. But how many unique statistics given a finite set is called the remaining degrees of freedom.

http://en.wikipedia.org/wiki/Degrees_of_freedom_(statistics)

Disco Boy · 19 May 2011 at 17:56

Do your own homework.

Eric's collar · 19 May 2011 at 17:57

From an exam I did today actually and not homework. It's additional maths level stuff and I didn't know anything about the remaining degrees of freedom or the formula so I just counted them 1 by by 1. Seems like I got it right then?