Which way do I calculate the F statistic in this problem:
DATA:
			northside	southside	eastside	westside	average
small properties	12		12		10		6		10
large properties	13		10		7		8		9.5
average			12.5		11		8.5		7		9.75 (GRAND MEAN)

QUESTION:
Want to find out if location of a property affects the number of properties sold by size.

Null H: Location does not affect.
Alt. H: Location does affect.

Grand mean: (12+12+10+6+13+10+7+8)/8 = 9.75
Between treatment sum of squares: 2(12.5-9.75)^2 + 2(11-9.75)^2 + 2(8.5-9.75)^2 + 2(7-9.75)^2 = 36.5
Within treatment: (12.5-12)^2+(13-12.5)^2+(12-11)^2+(10-11)^2+(10-8.5)^2+(7-8.5)^2+(6-7)^2+(8-7)^2 = 9

F = [36.5/(4-1)] / [9/(8-4)] ~ 5.41

OR

Grand mean: 9.75
Between treatment sum of squares: 4(10-9.75)^2+4(9.5-9.75)^2 = .5
Within treatment: (12-10)^2+(12-10)^2+(10-10)^2+(6-10)^2+(13-9.5)^2+(10-9.5)^2+(7-9.5)^2+(8-9.5)^2 = 45

F = [.5/(2-1)] / [45/(8-2)] ~ 0.7