/ Home


Time between Nerve Pulses

Keywords: exponential distribution, right skew data


The data gives the time between 800 successive pulses along a nerve fibre. There are 799 observations rounded to the nearest half in units of 1/50 second.


Data File (tab-delimited text)


Fatt, P., and Katz, B. (1952). Spontaneous subthreshold activity at motor nerve endings. Journal of Physiology 117, 109-128.
Cox, D. R., and Lewis, P. A. W. (1966). The Statistical Analysis of Series of Events. Methuen, London.
Jørgensen, B. (1982). The Generalized Inverse-Gaussian Distribution. Springer-Verlag.


The distribution of times is approximately exponential. Jørgensen (1982) and Cox and Lewis (1996) found some discrepancy from the exponential distribution. This can be seen in the lower tail of a plot of quantile residuals. There is no trend in the mean or the dispersion.

> summary(nerve)
 Min. 1st Qu. Median  Mean 3rd Qu. Max.
  0.5     3.5    7.5 10.95      15   69
> hist(y)

> out <- glm(nerve~1,family=Gamma)
> res <- qres.gamma(out,dispersion=1)
> qqnorm(res,ylab="Quantile Residuals")
> abline(0,sqrt(798/799))



Home - About Us - Contact Us
Copyright © Gordon Smyth