United States
Environmental Protection
Agency
Environmental Monitoring and Support
Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S4-86/023 July 1986
&EPA Project Summary
User-Friendly IBM PC Computer
Programs for Solving
Sampling and Statistical
Problems
Philip C. L. Lin
User-friendly IBM personal computer
programs for solving sampling and
related statistical problems have been
prepared. The programs are designed so
that persons without an in-depth under-
standing of statistics can easily use
them. Specific, detailed, written instruc-
tions for application of the programs are
provided in the full report. The computer
disc containing the programs will be
made available on request to the Envi-
ronmental Monitoring and Support
Laboratory—Cincinnati (EMSL-Cincin-
nati).
This Project Summary was developed
by EPA's Environmental Monitoring and
Support Laboratory. Cincinnati. OH. to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
Statistical techniques are useful in
assessing the quality of a sampling pro-
gram. Frequently, field persons engaged
in sample collection do not have the time
to thoroughly study and understand all
the statistics required to take a repre-
sentative sample. The computer programs
described herein were developed for
those people and are designed so that an
individual may use them and obtain the
benefits of the statistical package without
an in-depth understanding of the statis-
tics employed.
For those who wish to know more
details about the package, basic defini-
tions of statistics and descriptions of
statistical sampling programs on the disc
are presented in the Appendices of the
full report.
Typical Examples for Use of
Programs
In order to assist the user in working
the computer programs, a series of ques-
tions and answers has been developed.
Questions that those designing field
sampling programs may wish to have
answered are listed below, together with
the names of the computer programs
designed to answer the questions:
Question—How many samples must
be taken to reduce the anticipated
error to some reasonably fixed value?
Answer—Use program No. 8, "Deter-
mination of Sample Number," if the
reduction of the anticipated error is
based on the accuracy of the sample
variance. Use program No. 9, "Deter-
mination of Sample Number," if the
reduction of the anticipated error is
based on the accuracy of the mean.
Question—What is the probability of
an effluent exceeding a standard?
Answer—Use program No. 10, "Prob-
ability of Exceeding the Standard."
Question—How does one test wheth-
er a sample belongs in a particular
distribution?
Answer—Use program No. 11, "Hy-
pothesis Testing."
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Question—What is the sampling
frequency required to capture a sig-
nificant event in a long-term monitor-
ing program?
Answer—Use program No. 12,
"Power Spectrum Analysis."
Question—How does one determine
the sample mean, standard deviation,
and confidence intervals for the mean
and variance?
Answer—Use program No. 7, "Sam-
ple Mean, Standard Deviation, and
Confidence Intervals for Population
Mean and Variance."
Quest/on—Which program should
one use to correlate observed data in
a linear manner?
Answer—Use program No. 1, "Linear
Regression" to determine the linear
relationship and its correlation coef-
ficient.
Quest/on—A material is treated by
two different processes. Would there
be any justification for saying that a
difference existed between the two
processes? Which program should
one use to answer this question?
Answer—Use program No. 13, "Com-
paring Two Means."
Question—New equipment is used
to measure a compound, and it is
expected that the measurement uni-
formity would improve. The question
to ask is whether the improvement
(more uniformity) really exists or has
occurred by chance. Which program
should one use to test for the signif-
icant difference between variances
of two samples?
Answer— Use program No. 16, "Test
for Significant Difference between
Variabilities of Two Samples."
monitor, and, finally, the computer.
After a brief warm-up, you will see the
program menu:
* PROGRAM MENU PAGE 1 *
1. Linear Regression
2. Calculation of Normal Deviate Z
3. Calculation of the Percentage Area
of Normal Distribution (From Minus
Infinity to Normal Deviate Z)
4. Calculation of Student T
5. Calculation of the Percentage Area
of Student T Distribution (From
Minus Infinity to Student T)
6. Calculation of Chi Square
7. Calculation of Sample Mean, Stan-
dard Deviation, and Confidence
Intervals for the Population Mean
and Variance
8. Calculation of Sample Number
Based on the Accuracy of the
Variance
9. Calculation of Sample Number
Based on the Accuracy of the
Sample Mean
10. Calculation of the Probability of
Exceeding a Standard
11. Hypothesis Testing
12. Power Spectrum Analysis
13. Proceed to Next Page
14. Quit
• Type the desired option number and
press ENTER?
• Type an option number after the
question mark (?) and press ENTER.
The desired program will be loaded
into the computer. If you select option
number 13, then program memo on
page 2 will be shown as follows:
Type the desired option number and press
ENTER?
• After you run the desired program, you
have several choices'
(a) go back to program menu,
(b) do another calculation,
(c) quit,
by typing the requested option number
and press ENTER.
• If you want to abort program calcula-
tion, press CONTROL-BREAK key. If
you want to start over again, type
"EMSLSTAT" and press ENTER.
Instructions for Using Sampling
Programs on the IBM PC
Some individuals, especially those with
extensive computer experience, will be
quickly at ease with these programs. In
those cases, the instructions may be
bypassed, and the reader may begin to
run the programs immediately. For those
who need additional assistance, the
following instructions are provided:
• Place the program disc in Disc Drive A
and close the door.
• Turn on the power of each instrument
beginning with the printer, then the
* PROGRAM MENU PAGE 2
15. Comparing Two Means
16. Calculation of the Percentage Area
% in F-Distribution
17. Calculation of the F Value in F-
Distribution
18. Test for Significant Difference be-
tween Variabilities of Two Samples
19. Test for Significant Difference be-
tween the Population Variance and
the Sample Variance
20. Return to Previous Page
21. Quit
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The EPA author Philip C. L. Lin (also the EPA Project Officer, see below) is with the
Environmental Monitoring and Support Laboratory, Cincinnati, OH 45268.
The complete report, entitled "User-Friendly IBM PC Computer Programs for
Solving Sampling and Statistical Problems," (Order No, PB 86-203 783/AS;
Cost: $ 11.95, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring and Support Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business •
Penalty for Private Use S300
EPA/600/S4-86/023
0000329 PS
U S ENVIR PROTECTION AGENCY
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