Processing Ozone Data

In the past, we wrote about how we had to transfer ozone data we had collected on paper onto the computer. However, processing this data requires more work than simply typing the numbers into the computer program Igor before we can start doing analysis.


While data on foliar damage in our plants was recorded by hand and only needed to be typed in, the data for the amount of ozone in the air was recorded every five minutes by the ozone monitor, and transferred wirelessly to an Excel sheet on a computer indoors. This ozone data could be copy and pasted into Igor. We then decided to average the data for each hour so we would not be looking at every five minutes using a procedure in Igor. We then did similar work for data from the weather station as with the ozone data. We also looked for and removed outliers, which are points in the data that seem out of place and are likely the result of mechanical errors in the monitor. These outliers would show up as large spikes when the data was graphed. Another sign of an outlier would be if the amount of stippling, chlorosis, and necropsy began to decrease, since foliar damage can only increase or stay at the same amount. Data also needed to be removed if we knew there was a point in time when the ozone monitor had malfunctioned.


Once this work was done, we made diurnal graphs, which show the average amount of ozone over the course of a day or the average of another part of our data, such as temperature. We could also then graph any of our sets of data for specific lengths of time, and compare different data sets on graphs (for example, stippling vs. amount of ozone). By using graphs of the data, we can now begin to ask questions about what the data can tell us and make conclusions. However, each season, we repeat the process of collecting, entering, and working with new data from the garden.


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