Hi.

can anyone tell me how to calculate % RSD.

if we have three values, 93.92, 95.93 and 98.84.

how can we calculate %RSD from these.

Relative Standard Deviation (RSD) represents a measure of precision. RSD is sometimes called coefficient of variation (CV) and often is calculated as a percentage.

s = standard deviation

x = mean

RSD = s/x, as a percentage, (s/x) *100

Lets take your given values 93.92, 95.93 and 98.84 the average would be 96.23 with 2.47 (+/-) SD and RSD will be 2.57%.

[quote=Shahid Ali]Relative Standard Deviation (RSD) represents a measure of precision. RSD is sometimes called coefficient of variation (CV) and often is calculated as a percentage.

s = standard deviation

x = mean

RSD = s/x, as a percentage, (s/x) *100

Lets take your given values 93.92, 95.93 and 98.84 the average would be 96.23 with 2.47 (+/-) SD and RSD will be 2.57%.[/quote]

Is there a minimum number of readings required for calculating RSD? Can you calculate RSD for two numbers? Really appreciate if someone can explain with reasoning.

I do not find the reference about minimum number for RSD calculation but we always use at least 3 samples (triplicate) to measure the variation. with one sample we could get any information, with two samples we could not sure with the variation, with three or more samples we know the variation.