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June, 2002 How Good Are Your Samples? Over 70 people took the Sampling Challenge at the recent Texas Natural Resource Conservation Commission Environmental Trade Fair and Conference. Many were surprised at how variable different samples can be. The Sampling Challenge: Determine the percent lentils in a two-quart jar containing a mixture of lentils and lima beans based on a one-cup sample. That's 1/8 of the total lot size (8 ounces out of 64). Procedure: Participants scooped or poured from the jar into a measuring cup and weighed the sample on a small kitchen scale. Then they separated the beans by using a kitchen strainer. Next they weighed either the lentils or limas. Calculating the ratio allowed them to determine the percent lentils in the sample. It took less than two minutes to do. Results: How representative were the samples? Not very. In one of the jars, the true percentage of lentils was 33%, but the percentages people got from their samples ranged from 16% to 55% !! Moral: Your samples may not be as representative as you think! More information about variation in sampling solids, liquids, and gases is available in the Short Course September 16-17, 2002, at Texas Tech University and in the short introductory book A Primer for Sampling Solids, Liquids, and Gases. TNRCC Environmental Trade Fair and Conference: If you missed this annual event in Austin, May 6-8, be sure to go next year. There are lots of Exhibitors---from environmental service companies, to labs, to equipment manufacturers. One-hour presentations can get you up to speed on new regulations, legislation, permitting, certification, accreditation, and occupational licensing. There are also specialty lectures on waste management, pollution prevention, and technical services. Texas Environmental Excellence Awards:
These awards honor the State's most outstanding waste reduction and
pollution prevention projects. Among the 12 awards given, two were very
special. One went to a group of fourth and fifth graders at Condit
Elementary School in Bellaire, Texas, in the Houston Independent School
District. Using information from the Internet, they monitor nearby ozone
levels four times daily and display different colored flags to notify the
public of the current ozone concentration. Another impressive award went
to Stephanie Lacy, a high school student in Bandera, Texas,
who began a community paper-recycling project in Bandera County. It has
been a big success, saving 438 cubic yards of landfill space. The program
is expected to collect over 120 tons of paper this year! Congratulations! Send This Information To a Friend "Your decisions are
only as good as your samples." Newsletters | About
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