Creating a Graph for PPM

[erikws]

I could really use your help. We are having trouble graphing our results. The project is lead testing in soil of area schools.
Our lead testing kit gives us results of 0, 1 - 3 ppm, 5 ppm, 10 ppm 25 ppm and over 50 ppm.
We conducted tests on 4 sites at each school. Testing 10 times for each site. All of our results are 0 or 1 - 3 ppm.
We have only done graphs in the past on whole numbers finding averages and are unsure how to do it using 1 - 3 as a result. We have searched the internet, our excel spreadsheet handbook, both parents and high school aged brother and we are unable to proceed. My project is due on the 10th. Any and all help is greatly appreciated.
Thanks S.

[ChrisG]

Were the 10 tests for each site done on the same sample, or on 10 samples taken in close proximity?

I would try a few different approaches and see which one works the best for explaining your results. Because you really only have two values for your variable (0 and 1-3ppm), you could present it as "a frequency of detection", which would be the number of times out of 10 that you detected 1-3ppm lead at any given site. Alternatively, you could choose an average value of 2ppm for the 1-3 ppm detections, and then average the 10 replicates for each site. Whatever you do, make sure that you explain it clearly in your reports and presentations.
Good luck!
Chris

[erikws]

Using a guadrat we took 4 differnt samples of 1/4 cup each from each site. The samples were 1 liner ft appart. We then mixed these together for each site sample. Each school had 4 site locations. One next to the building, one next to the bus ramps, one in the drain or run off area and one in a central play area. We tried to pick the same 4 enviroments at each school.
I like both of your idea's we will give them a try tonight. Thank you so much for you help.
S,

[adance]

Hi Erik,

If I understand your data correctly, I think a sort of bar graph or histogram would be most appropriate.

I'd do it like this:

Along the x-axis you have four categories for the four sites you tested. Then, within each of the four sections, divide it into further sections: 0, 1-3, 5, 10, 25 ppm. Then the y-axis is "number of times detected" and you'll have two bars for each site, a 0 and a 1-3 bar.

Excel puts together these kinds of graphs pretty easily.

Hope this helps.

[erikws]

Thank you so much.
This is very helpful!!!