Keyword Analysis & Research: where does the lehman formula come from

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
where does the lehman formula come from	1.63	0.5	7514	77	39
where	0.58	0.3	3931	10	5
does	1.42	0.4	9673	56	4
the	1.95	0.8	9984	75	3
lehman	1.83	0.2	6205	73	6
formula	0.83	0.4	5759	100	7
come	0.56	0.4	4889	53	4
from	0.59	0.8	2469	13	4

Keyword	CPC	PCC	Volume	Score
where does the lehman formula come from	1.86	0.2	1976	74