cv: Coefficient of variation (CV)

In iemisc: Irucka Embry's Miscellaneous Functions

Coefficient of variation (CV)

Description

This function computes the sample coefficient of variation (CV).

Usage

cv(x, na.rm = FALSE)

Arguments

x	numeric vector, matrix, data.frame, or data.table that contains the sample data points.
na.rm	logical vector that determines whether the missing values should be removed or not.

Details

CV is expressed as

\frac{s}{\bar{x}} \cdot 100

s

the sample standard deviation

\bar{x}

the sample arithmetic mean

Value

coefficient of variation (CV), as a percent (%), as an R object: a numeric vector or a named numeric vector if using a named object (matrix, data.frame, or data.table). The default choice is that any NA values will be kept (na.rm = FALSE). This can be changed by specifying na.rm = TRUE, such as cv(x, na.rm = TRUE).

Author(s)

Irucka Embry

Source

1. r - How to not run an example using roxygen2? - Stack Overflow answered and edited by samkart on Jul 9 2017. (Also see the additional comments in response to the answer.) See https://stackoverflow.com/questions/12038160/how-to-not-run-an-example-using-roxygen2.

2. devtools - Issues in R package after CRAN asked to replace dontrun by donttest - Stack Overflow answered by Hong Ooi on Sep 1 2020. (Also see the additional comments in response to the answer.) See https://stackoverflow.com/questions/63693563/issues-in-r-package-after-cran-asked-to-replace-dontrun-by-donttest.

References

1. Masoud Olia, Ph.D., P.E. and Contributing Authors, Barron's FE (Fundamentals of Engineering Exam), 3rd Edition, Hauppauge, New York: Barron's Educational Series, Inc., 2015, page 84.

2. Irwin R. Miller, John E. Freund, and Richard Johnson, Probability and Statistics for Engineers, Fourth Edition, Englewood Cliffs, New Jersey: Prentice-Hall, Inc., 1990, page 25, 38.

See Also

sgm for geometric mean, shm for harmonic mean, rms for root-mean-square (RMS), relerror for relative error, approxerror for approximate error, and ranges for sample range.

Examples

# Example 2.60 from Miller (page 38)

library(iemisc)

x <- c(14, 12, 21, 28, 30, 63, 29, 63, 55, 19, 20)
# suspended solids in parts per million (ppm)

cv(x)


# using a matrix of the numeric vector x
mat1 <- matrix(data = x, nrow = length(x), ncol = 1, byrow = FALSE,
        dimnames = list(c(rep("", length(x))), "Samples"))
cv(mat1)


# using a data.frame of the numeric vector x
df <- data.frame(x)
cv(df)


# using a data.table of the numeric vector x

library("data.table")

dt <- data.table(x)
cv(dt)



# modified Example 2.60 from Miller (page 38)
xx <- c(14, 12, 21, 28, 30, 63, 29, 63, 55, 19, 20, NA)
# suspended solids in parts per million (ppm)

cv(xx) # na.rm = FALSE is the default
cv(xx, na.rm = TRUE)





# See Source 1 and Source 2

# Example 3

# Please see the error messages

library(iemisc)

try(cv(0))
try(cv(1))
try(cv(1003.23))






# Example 4 - from the archived cvcqv README

xu <- c(0.2, 0.5, 1.1, 1.4, 1.8, 2.3, 2.5, 2.7, 3.5, 4.4, 4.6, 5.4,
5.4, 5.7, 5.8, 5.9, 6.0, 6.6, 7.1, 7.9)

results2 <- cv(xu)
results2

iemisc documentation built on Sept. 25, 2023, 5:09 p.m.