quantchem (version 0.13)

vstat: Variability statistics of quantitative analysis results

Description

Estimate error propagation of results (inter- and intra-day, inter- and intra-batch etc.)

Usage

vstat(x, ...)

Arguments

x

a data frame of results. Each column contain one serie of results

...

optionally, more data frames, if additional factor is taking into account

Value

The ANOVA object is returned, containing additional columns:

Percent

Percentage indication of error propagation (total sum of squares is 100 percent

SD

Standard deviation (square root of Mean Sq)

RSD

Relative standard deviation (coefficient of variation)

There are also additional rows - lowest row gives overall (total) error, and if function is called on multiple data-frames, a row containing variability between all series (sum of within-groups and between-groups) is given.

Details

This function performs one-way or two-way ANOVA on given results and prints summary in the usable way. If we are checking variability only between and within one kind of series (days, batches), we construct a data frame with a result sets in its columns and call this function on such data.frame. In this case, we get variability analysis of between-series and within-series. If we want to check variability additionally for example between weeks, we group results in data frames for each week and call the function on all data frames. This will summarize error propagation concerning series and groups.

See Also

dstat

Examples

set.seed(1234)
week1 = data.frame(mon=rnorm(6),tue=rnorm(6),wed=rnorm(6),thu=rnorm(6),fri=rnorm(6))
week2 = data.frame(mon=rnorm(6),tue=rnorm(6),wed=rnorm(6),thu=rnorm(6),fri=rnorm(6))
week3 = data.frame(mon=rnorm(6),tue=rnorm(6),wed=rnorm(6),thu=rnorm(6),fri=rnorm(6))
week4 = data.frame(mon=rnorm(6),tue=rnorm(6),wed=rnorm(6),thu=rnorm(6),fri=rnorm(6))
week1=week1+15;week2=week2+15;week3=week3+15;week4=week4+15
vstat(week1)
vstat(week1,week2,week3,week4)