Keyword Analysis & Research: what does the term sigma mean

Keyword Analysis

Keyword	CPC	PCC	Volume	Score	Length of keyword
what does the term sigma mean	1.2	0.8	8437	59	29
what	0.14	0.1	7317	88	4
does	0.86	0.9	5150	8	4
the	0.13	0.7	8445	28	3
term	1.4	0.5	4982	14	4
sigma	0.89	0.2	2990	68	5
mean	1.14	0.5	1552	57	4

Keyword	CPC	PCC	Volume	Score
what does the term sigma mean	1.17	0.3	5441	90