WolmanCI: Calculate the percentile sizes and grain size confidence...

In bceaton/GSDtools: Tools for analyzing pebble counts used to measure river bed surface texture

Description

WolmanCI is a function that uses cumulative frequency distribution data for Wolman or grid-by-number samples of bed surface texture to estimate the value of user-specified percentiles. The function also uses the binomial distribution to estimate the confidence intervals corresponding to a user-specified confidence level, based on the number of grain size measurements that were used to construct the cumulative frequency distribution.

Usage

WolmanCI(cfd, n, P = seq(5, 95, 5), equaltail = T, alpha = 0.05)

Arguments

cfd	is a data frame providing a list grain sizes in the first variable and the corresponding cumulative proportion finer in the second. The grain sizes should be recorded in mm, and the proportion finer in [0,1].
n	is the total number of observations upon which the cumulative frequency distribution in cfd is based
P	numeric vector of percentiles to estimate. The default is to estimate the 5th to the 95th percentile, in increments of 5.
equaltail	is a logical variable that determines whether the calculations of the confidence interval are based on an approximation with equal areas in each tail (the default), or based on the exact binomial solution with a coverage of at least 95%
alpha	the desired confidence level for which to calculate a confidence interval in [0,1].

Details

The function returns a data frame listing the estimate of each percentile, the upper limit, and the lower limit.

bceaton/GSDtools documentation built on June 7, 2019, 12:53 a.m.