Environmental Engineering Reference
In-Depth Information
described and established. All of this is also related back to the project notebook and the
question of the use of bar codes.
3.14. STATISTICS
All sampling and analysis will have variation, which is normal and expected. If variation
does not occur it is reasonable to suspect that the data are in error. Because of this
variation it will be essential to analyze the analytical results using statistics. These tools
will be used to be determine if samples taken at different places and times have different
amounts of a particular component or not. In many cases it will be important to know if
the results are within acceptable limits or not. Statistical analysis will also be important to
determine if an analytical result is an outlier or in error. Statistical analysis of analytical
results thus will be essential.
What statistical tools will be needed? The first calculation to be made is the mean and
standard deviation of the samples. Subsequently a t-test will be needed to determine if
two samples are different or the same or if the sample is within acceptable limits. This
may be between two samples from the same or similar places in the field or samples
obtained at different times. In all probability some more advanced geostatistical tools will
be needed to graphically represent the level of components of interest. These
representations will be used to understand what is happening in the field. They will also
be needed to explain the sampling needs to others, including the public.
Because there are many statistical tools and packages, some evaluation of the various
packages may be needed. For the statistical tools and programs to be most effective
personnel must know how to use them before sampling begins. Often the more powerful
programs will require more learning before they can be used effectively, and thus it may
be more useful to use a statistical program that the operator knows how to use rather than
to try to learn a new program. Another thing to remember is that the tools chosen must be
compatible with the computer system to be used.
In all cases it is essential to have a statistician check the statistical analysis for errors
and to make sure the correct tools have been used.
3.15. OTHER TOOLS TO CONSIDER
The use to be made of other sampling tools needs to be decided upon. How much use will
be made of GPS? What type of receiver will be needed? Is GPR called for? How much or
how will remote sensing and GIS be used? If these tools are to be used, what computer
software will be needed and what computer system will be used to collect and store the
data?
A word of caution would be that some of these applications use large amounts of
computer storage space. When deciding on a computer, both RAM and hard disk storage
should be maximized, thus RAM of 512 MB and an 80-GB hard drive are the minimum
recommended. Removable storage for presentations and backup must also be provided.
Either a CD or DVD recorder will be best suited to this task. Because CDs are
 
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