Cali Water Usage
California Water UsageResearch QuestionWhat factors influence
California residences daily water usage?
HypothesesH0 (Null): The independent variables have no
statistically significant associations with domestic daily water
usage/person (gal.).HA (Alternative): The independent variables do
have statistically significant associations with domestic daily
water usage/person (gal.).
By Gabby Hernandez, Meme Torio, Kendall Thompson
1SourcesU.S. Geological SurveyCollected from local, state, and
federal agenciesNational Oceanic & Atmospheric
AdministrationCollected from Climatic Weather Stations2010 U.S.
CensusCollected by the federal government (US Census Bureau)Sample
SizeAll 58 California CountiesDependent Domestic Water Usage (Daily
use/Person) gals. Independent Annual Precipitation (in.) Avg.
Annual Temp. (F) Avg. Household Size % of Population w/ BA or
higher (25+) % Black or African American % White (non-Hispanic or
Latino) % Hispanic or Latino
About Our Data
VariableCoefficientsStandard ErrorP-ValueTotal Precipitation
(In.)-0.6950.2460.007Mean Annual Temp. (F)1.2110.6150.055% Black or
African American0.8541.3420.528% White (non-Hispanic or
Latino)1.4470.5540.012% Hispanic or Latino-0.2390.550.666% of Pop.
With BA or higher (25+)-0.750.3680.038Avg. Household Size
55.72421.8030.014F-stat6.287Significance F0.000Adjusted
R-square0.394Number of Observations58
At the 95% confidence level the following variables were
statistically significant:Total Annual Precipitation, % of CA
residents who are White, % of Population w/ BA or Higher (25+), and
Average Household Size.
Ex: As the percentage of the population (25 and older) with
Bachelors degrees or higher increases by 1%, daily domestic water
usage per person decreases by 0.75 gallons.
*The following variables were also included in the data, but
were omitted from our regression because they were statistically
insignificant:Agricultural Income, Land Area (sq. mi), Population
Density (tot. pop/sq. mil), Median Household Income, and Private
Nonfarm Employment.
Results:A multiple regression analysis was conducted to examine
7 potential predictors relationship with California residents daily
water usage/person (gal.). The multiple regression model with all 7
predictors produced an adjusted R2 = 0.394 (meaning 39.4% of the
dependent variable, Californias residents daily water usage/person
(gal.), is responding to the independent variables).F(7, 58) =
6.287 > F-crit.: indicates all coefficients of the independent
variables are not statistically equal to zero.P = 0.000 < 0.005:
rejects the H0: stating that at the 95% confidence level, there is
a significant relationship between the independent variable and
California residents daily water usage/person (.gal) (4 out of 7
were statistically significant).Looking at the p-values < 0.05
for each predictor we can state:California residents daily water
usage/person (gal.) has a moderately statistically significant
direct association with percentage of Californians that are white
AND average household size. California residents daily water
usage/person (gal.) has a moderately statistically significant
inverse association with total precipitation AND percentage of CA
population with a B.A. or higher (25+)Possible improvements:Expand
sample size to every CA city. Examine data from multiple years.
This study only considers data collected from 2010.