In this activity, you will compare fecal coliform data collected on dry days and on days after it rained that was obtained in 1998-99 to data collected in 1997-98 and 1993-94. This analysis is important because the city has been installing the new sewer system since 1993. We want to find out if the work completed to date has made a difference in the fecal coliform concentrations in the creek on rainy days. Data from the different collection sites along Blackwater Creek are combined for both the Dry and Wet data. Therefore, you will be using the grand means for each group in your analysis.

Using Excel or the TI-83, calculate the grand mean of each year's study, wet and dry. Compare these values by generating a bar graph of the means. This data exists in three files; one is in Excel Data format, one in Text, and one in TI-83 Group format. To use the TI-83, you'll need to import the TI-83 group file.

After making the bar graph it is important to analyze what it is telling you. For example, is there a trend shown by the graph? What does this graph show about the new sewage system?

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Original work on this page provided by Jon Giffin, Shirley Isaac, and Nykia Douglas (Class of '00).

Copyright © 1999 Central Virginia Governor's School for Science and Technology Lynchburg, VA