Keyword Analysis & Research: what does sf mean in measurement

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
what does sf mean in measurement	0.71	0.5	3702	40	32
what	0.79	0.5	8398	78	4
does	1.62	0.3	1527	31	4
sf	0.37	0.9	3309	87	2
mean	1.63	0.2	1757	65	4
in	0.55	0.2	4183	21	2
measurement	0.79	0.2	7198	99	11

Keyword	CPC	PCC	Volume	Score
what does sf mean in measurement	1.21	0.2	9549	49