[R] how to interpret t.test output
Felipe Carrillo
mazatlanmexico at yahoo.com
Sat Aug 9 22:31:33 CEST 2008
# Hi all:
#I got a vector with fish lengths(mm)
# Can someone help me interpret the output of
# a t.test in plain english?
# Based on the t.test below I can say that
# I reject the null hypothesis because
# the p-value is smaller than the the significance
# level(alpha=0.05). What else can I conclude here?
Ho = 36 mm
Ha <> 36 mm
fishlength <- c(35,32,37,39,42,45,37,36,35,34,40,42,41,50)
t.test(fishlength,mu=36)
One Sample t-test
data: fishlength
t = 2.27, df = 13, p-value = 0.04087
alternative hypothesis: true mean is not equal to 36
95 percent confidence interval:
36.14141 41.71573
sample estimates:
mean of x
38.92857
# I also would like to know how to interpret the output
# when mu=0? Notice that the p-value from the t.test above
#is different from this t.test. Are we trying to reject the null
# hypothesis here too?
t.test(fishlength)
One Sample t-test
data: fishlength
t = 30.1741, df = 13, p-value = 2.017e-13
alternative hypothesis: true mean is not equal to 0
95 percent confidence interval:
36.14141 41.71573
sample estimates:
mean of x
38.92857
Thanks in advance for your help.
Felipe D. Carrillo
Supervisory Fishery Biologist
Department of the Interior
US Fish & Wildlife Service
California, USA
More information about the R-help
mailing list