Where { s _ { \ rm ln } } \, is the sample standard deviation of the data after a natural log transformation . ( In the event that measurements are recorded using any other logarithmic base, b, their standard deviation s _ b \, is converted to base e using s _ { \ rm ln } = s _ b \ ln ( b ) \,, and the formula for \ widehat { c _ { \ rm v } } _ { \ rm ln } \, remains the same . ) This estimate is sometimes referred to as the " geometric CV " in order to distinguish it from the simple estimate above.
