have a look at the online help file of ?quantile(); check also:

x <- c(67.12, 64.51, 62.06, 55.45, 51.41, 43.78, 10.74, 10.14)
sapply(1:9, function (i) quantile(x, c(0.05, 0.95), type = i))


I hope it helps.

Best,
Dimitris


ANJAN PURKAYASTHA wrote:
Hi,
A simple quantile question:
I need to calculate the 95% and 5% quantiles (aka percentiles) for the
following data:
67.12
64.51
62.06
55.45
51.41
43.78
10.74
10.14

if I use the formula: 95% quantile point= 95 (8+1)/100, I get the 8.55th
point as the 95% quantile. Which does not make too much sense as I have only
8 data points.
The other option is to use (95*8)/100 = 7.6th data point (which can be found
by interpolation between the 7th and 8th data points).
Reportedly, the second formula is not too accurate. However in my case the
first formula does not make much sense.

Any advice?

TIA,
Anjan


--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus Medical Center

Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014

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