- Statistics use the standard metrics for coefficients of correlation and determination, R and R2. These primarily reflect correlation of changes in cost relative to (1) consumption and (2) rates. Derivation of these metrics is in this linked Excel spreadsheet. Correlation coefficients (R) were computed from matrices containing data for each individual billing period.
- Coefficients of determination (R2) were derived for two factors, consumption and rates. These account for 99.0% of total cost. The remaining 1.0% of
total cost involves other factors.
for changes in rates are not shown: These are less informative, since
almost all rate changes occur annually instead of per billing period.
Rate-related effects can be recognized in the graphs by visually
comparing the year-specific plotted data.
2013 was the most demanding year of the recent drought. Timing of rain
was a factor in producing high levels of drought stress to landscaping:
The period from last spring rain to first fall rain was a full month
longer than usual.
- All data are from the billing
records of this web site's author, representing a home in El Dorado
Hills. Cost used is the total billed water cost, including line/cover
charges. This is for a residential account in El Dorado Hills whose
average water consumption is nearly identical with the average
identified in EID's 2010-2011 Cost Of Services Study.
data will be updated later in December, 2016 to inclorporate data
for the year's final billing period. (This draft predates the December
available in saved billing records began with the third billing period
of 2011. Consequently, the graphs show bimonthly consumption and cost
for only four bimonthly billing periods in 2011 and cannot show
year-to-date totals for 2011.
- Water consumption
data for the December/January 2015/2016 billing period was not
available due to failure of the home's original water meter, which
seized and reported zero flow after 25 years in service. Consumption
for that period is reported as 1,200 cubic feet, based on the
approximate median for the same period from other bills.
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