SAMPMEAN: Learn About
Sampling
This simple program is included as a
useful tool for teaching about sampling. It has two
views. A histogram of the current random sample's values,
and a histogram of the sample mean values for the samples thus far
selected. When prompted, One toggles between the two views
with a "T".
The program computes a population
mean and asks for a sample size and a number of trials. It then
picks a random sample (with replacement) of the specified size
from the population. It displays on a histogram the location of
the population mean with > and with a s for the location of the
current sample's mean. Each time "N" is pressed, another sample is
selected and its sample mean value is included in the histogram of
the sample means. If, at any time, "F" is pressed, the remainder
of the trials samples are selected, one by one, and you see all
the resulting sample means on the histogram us sample means.
Throughout the program execution, running statistics of the
samples are listed.
SEQUENCE OF
PROGRAM PROMPTS
Name of File with Population Distribution {.TXT} ?
File with list of integer values.
Alternately, enter “CON” and type in any number of values followed
by <Ctrl>Z. The population to be sampled is described
in an ASCII text file. The program expects a list of integers
separated by blanks, commas, or carriage returns (or one can
answer CON to the request for the file name and type any number of
numbers from the keyboard (including carriage returns) followed by
a <Ctrl>Z). Either the file or the keyboard-entered list
constitutes the (finite) population of integer values under
consideration. A population can be generated by the ADFUTIL
program. But the ADF file must be edited with a plain text
editor (like notepad) to remove the header and number of rows and
columns.
Sample Size
Size of the sample drawn with
replacement from the population.
Number of Trials ?
Number of different random samples
to be selected.
Histogram Lower Limit {xxx.xx} ?
Histogram Upper Limit {xxx.xx} ?
Histogram Interval {xxx.xx} ?
This gives the user some control
over the histogram of sample values selected and the histogram of
the sample means. The defaults should often work, but a neater
histogram can be produced is you supply these values. Generally,
pick a number for the interval width at least as large as the
default value to keep the histogram fitting on the screen.
[T]oggle Current View, [N]ext Sample, [F]ast ? T
Hitting T toggles between the
sample view and the cumulative view of the sample means. N
goes to the next sample. Hitting F runs through the rest of the
samples creating a histogram of the sample means. In the
histograms the population mean is shown by a >, the current
sample mean by a s, and the grand mean of the sample means as a S.
SAMPLE RUN
File with Any Number of Integer Population Values {.TXT} ? test
Population Values Read: 40
Population Mean: 147.3000
Sample Size ? 10
Number of Trials ? 100
Data Values Range from 6 to 272
Histogram Lower Limit {6} ? 0
Histogram Upper Limit {272} ? 300
Histogram Interval {16.0000} ? 15
Random Generator Seed (0 to set from clock) {0} ?
SampleNo SampMean Cur Mean Std Err Pop Mean Outside
1 154.7000 154.7000 0.0000 147.3000 0
Sample Values (P=Population Mean, s=Current Sample Mean
0.0000 1 |*
15.0000 0 |
30.0000 0 |
45.0000 1 |*
60.0000 0 |
75.0000 1 |*
90.0000 0 |
105.0000 0 |
120.0000 2 |**
135.0000 1 P*
150.0000 0 s|
165.0000 0 |
180.0000 0 |
195.0000 0 |
210.0000 0 |
225.0000 1 |*
240.0000 1 |*
255.0000 1 |*
270.0000 1 |*
285.0000 0 |
300.0000 0 |
[T]oggle Current View, [N]ext Sample, [F]ast ? T
SampleNo SampMean Cur Mean Std Err Pop Mean Outside
1 154.7000 154.7000 0.0000 147.3000 0
Means of Samples (P=Population Mean, s=Current Sample Mean, S=Mean of Sample Means)
0.0000 0 |
15.0000 0 |
30.0000 0 |
45.0000 0 |
60.0000 0 |
75.0000 0 |
90.0000 0 |
105.0000 0 |
120.0000 0 |
135.0000 0 P
150.0000 1 S|s
165.0000 0 |
180.0000 0 |
195.0000 0 |
210.0000 0 |
225.0000 0 |
240.0000 0 |
255.0000 0 |
270.0000 0 |
285.0000 0 |
300.0000 0 |
[T]oggle Current View, [N]ext Sample, [F]ast ? f
SampleNo SampMean Cur Mean Std Err Pop Mean Outside
1 154.7000 154.7000 0.0000 147.3000 0
[T]oggle Current View, [N]ext Sample, [F]ast ? f
SampleNo SampMean Cur Mean Std Err Pop Mean Outside
100 126.0000 146.0940 24.9743 147.3000 0
Final Means of Samples (P=Population Mean, s=Current Sample Mean, S=Mean of Sample Means)
0.0000 0 |
15.0000 0 |
30.0000 0 |
45.0000 0 |
60.0000 1 |X
75.0000 2 |XX
90.0000 3 |XXX
105.0000 5 |XXXXX
120.0000 18 |XXXXXXXXXXXXXXXXXs
135.0000 28 SPXXXXXXXXXXXXXXXXXXXXXXXXXXXX
150.0000 24 |XXXXXXXXXXXXXXXXXXXXXXXX
165.0000 13 |XXXXXXXXXXXXX
180.0000 4 |XXXX
195.0000 0 |
210.0000 2 |XX
225.0000 0 |
240.0000 0 |
255.0000 0 |
270.0000 0 |
285.0000 0 |
300.0000 0 |
Program End
OK to Close Program Window {Y} ?
Test Data
6, 151, 217, 121, 13, 272, 68, 250, 193, 229, 16, 216, 83,
62, 241, 199, 201, 24, 120, 168, 127, 247, 54, 147, 222, 54, 33,
83, 105, 196, 226, 210, 237, 264, 243, 205, 167, 100, 113, 9
Page Last Updated: 25 August 2023
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