Yeast pitching rate

I normally use half of the sediment from the previous brew to add to the new brew. Often I have a 2 inch head within 4 hours, and a 4% alcohol beer finishes fermenting and clears in only 3 to 4 days. does the amount of yeast pitched affect the finished beer?

It absolutely affects the finished beer. Pitching rates affect attenuation and flavor profiles almost as much as fermentation temperature does. You can find a good pitching rate calculator here:

http://www.mrmalty.com/calc/calc.html

I found this post from another thread helpful:

https://www.homebrewtalk.com/showpost.php?p=725127&postcount=20

thanks for those two responses, as a newbie I don't know if I can ask a related question here, or whether I have to start a new thread, but here goes, would it be better to skim off the head on day 2 and make a starter from that, rather than use the sediment?

As stated in another thread, skimming can cause more problems than it solves. You can too easily introduce spoiling microbes. It is wise to wait until you rack off the yeast cake and harvest from that.

Skimming is not something a homebrewer needs to do. Commercial breweries which still adhere to the practice skim because they need to pitch yeast at least once per day. You don't, so just be patient.

Cheers,

Bob