Ranking the following from most stable to least stable

[ahazen]

I need help ranking the following from most stable to least stable:
-(CH3)2C=CHCH2 with dot over the CH2
-(CH3)2CHCHCH3 with dot over the 2nd CH
-(CH3)2CCH2CH3 with dot over the C
-(CH3)2CHCH2CH2 with dot over the CH2

the dots represent the primary, secondary, and tertiary radicals

thank you:)

 

[zhermes]

Well, what determines the stability of a radical compound?