Experiment #2
Resistor Statistics
• The object of this experiment is to generate a
histogram demonstrating how many resistors in
a sample of the same nominal value meet
specifications.
• A histogram is a plot that shows how many of an
item fall into specific “bins”.
1
Procedure
• Each student will be given a sample of resistors
having the same nominal value.
• For each resistor:
– Determine the nominal value from the color code.
– Measure and record the resistance of each resistor in
the sample.
– Enter your data in an Excel table as shown on the
next page.
– Plot a histogram bar graph of the measured values
and determine the mean and the standard deviation
of the resistance values.
2
Example Histogram
Table Generated by Excel
Raw Data
Value
1
1000
2
1050
3
990
4
1075
5
950
6
899
7
1102
8
1080
9
1005
10
1020
Number of
resistors with
values < or =
to 900
Bin
Number of resistors
with values from
1051 through 1100
Frequency
900
1
950
1
1000
2
1050
3
1100
2
More
1
Plot of Excel Table Data
Histogram for 1000 Ohm Resistors
3.5
Number in Range
R#
3
2.5
2
Frequency
1.5
1
0.5
0
900
950
1000
1050
Measured Value
1100
More
3
Data for Experiment #2
TEAM #
NAMES
NOMINAL VALUE
TOLERANCE
=
ALLOWABLE RANGE
MEASURED
VALUE
1
2
3
4
5
6
7
8
9
10
AVERAGE
STD DEV
=
=
4
Preparing to Plot a Histogram
• Before you start to generate a plot, create a
sequence of 5 numbers in your Excel sheet,
equally spaced, from the minimum of your
allowable range to the maximum of your
allowable range.
• For example, if the range was 400-800, I would
generate the following sequence:
400
500
600
700
800
5
Generating a Histogram Table
•
•
•
•
Click on the “Data” pull-down menu
Select “Data Analysis”
Select “Histogram”
For Input Range
– Enter the cell range with your resistance
measurements (e.g. a4:a20)
• For Bin Range
– Enter the cell range of your 5 values
• For Output Range
– Enter the cell that you want to be the upper
left corner of your histogram table
6
Generating a Histogram Plot
• Select (click and drag the cursor over) the table
that was created using the histogram command
• Click on the “Insert” pull down menu
• Select “Column”
• Select chart type
• You’ll see a preview of your plot, click “next”
• Enter a label for the x axis and change the plot
title from “frequency” to something with your
nominal resistor value in it, click “next”
• Select “as object in sheet 2” in last step then
click “finish”
7
What needs to be turned in
• A printout of the data table including:
– The original data
– The histogram table
– The histogram plot
8