SewageR Documentation

Chlorinating sewage data from Preece (1982, Table 9)

Description

This dataset presents 8 paired data corresponding to log coliform densities per ml for 2 sewage chlorination methods on each of 8 days.

Usage

data(Sewage)

Format

A dataframe with 8 rows and 3 columns:

[,1] Day numeric
[,2] Method_A numeric log density
[,3] Method_B numeric log density

Source

Wetherill, G.B. (1972) Elementary Statistical Methods, 2nd ed. Chapman and Hall: London.

References

Preece, D.A. (1982) t is for trouble (and textbooks): a critique of some examples of the paired-samples t-test. The Statistician, 31 (2), 169-195.

Examples

data(Sewage)

# Visualising
with(Sewage,plot(paired(Method_A,Method_B),type="profile"))

# Basic paired t-test
with(Sewage,t.test(paired(Method_A,Method_B)))

# Influence of the 0.1 rounding on the t-test
 with(Sewage,t.test(Method_A-Method_B-0.1))
 with(Sewage,t.test(Method_A-Method_B+0.1))