Bacteria from Delaware River water entering the Torresdale Filter of the Philadelphia water supply 1913.

The number of bacteria per cubic centimetre was measured daily for river water entering the Torresdale filter of the Philadelphia water supply through the whole of 1913.

bacteria

Format

A data frame with 22 rows and 2 variates:

count

Number of bacteria per cc.

percentTime

Percent of days (out of 365) having bacteria count less than or equal to the measured count.

Source

"The Element of Chance in Sanitation", George C. Whipple, Journal of the Franklin Institue, Volume 182, July and August (1916), pp. 37-59 and 205-227. Data taken directly from Figure 22, page 209.

Details

Rather than the individual daily results, recorded here are 22 values together with the percentage of days whose value was less than or equal to the recorded value. These quantiles are therefore based on 365 daily measurements.

Values were taken from a logarithmic-normal probability plot dated January 21, 1915 as it appeared in Figure 22 of George C. Whipple's 1916 (Part 2) paper on the ``Element of Chance in Sanitation''. This paper introduces logarithimic-normal probability paper (or a log-normal qqplot).

with(bacteria, plot(qnorm(percentTime/100), log(count,10), type="o")) reproduces Whipple's 1915 plot.

with(bacteria, qqtest(data=count, p=percentTime/100, np=365, dist="log-normal", type="o")) will effect a qqtest plot for this data. More detail can be had from: with(bacteria, qqtest(data=log(count, 10), p=percentTime/100, np=365, dist="normal", type="o"))