Stats for Business and Economics

Assignment: Statistics for Business and Economics

1. (40 points) Please use the MTBE Excel file to solve this question.

Groundwater contamination in wells.

In New Hampshire, about half the counties mandate the use of reformulated gasoline. This has led to an increase in the contamination of groundwater with methyl tert-butyl ether (MTBE). Environmental Science & Technology (Jan. 2005) reported on the factors related to MTBE contamination in public and private New Hampshire wells. Data were collected for a sample of 223 wells. These data are saved in the MTBE file.

a) (4 points) Which of the variables are qualitative and which are quantitative?

b) (8 points) Using StatCrunch, create charts to describe each of the quantitative and each of the qualitative variables. c) (5 points) Use side-by-side bar charts to compare the proportions of contaminated wells for private and public well classes.

d) (5 points) Use side-by-side bar charts to compare the proportions of contaminated wells for bedrock and unconsolidated aquifers.

e) (8 points) What inferences can be made from the bar charts, parts b-d?

f) (4 points) Create a Scatter Diagram for “pH” versus “DissOxy”. Briefly describe the relationship.

g) (6 points) Calculate the Summary Statistics for pH, DissOxy, and MTB. Using the inner fences as boundary, are there any outliers?

Solution:

a) Which of the variables are qualitative and which are quantitative?

Qualitative Variables | Quantitative Variables |

WellClassAquiferDetection | pHDissOxyDepthDistanceMTBE |

b) (8 points) Using StatCrunch, create charts to describe each of the quantitative and each of the qualitative variables.

c) Use side-by-side bar charts to compare the proportions of contaminated wells for private and public well classes

d) (5 points) Use side-by-side bar charts to compare the proportions of contaminated wells for bedrock and unconsolidated aquifers.

e) What inferences can be made from the bar charts,...