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Dataplot Solution to the Data Analysis Problem
Problem Setup
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An analyst has a data set consisting of a response variable
and three independent variables (factors). Determine if the
factors affect the response. Determine if there is interaction
between the factors. Perform an analysis of variance. Perform
a graphical analysis of variance.
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Dataplot Program
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This is demonstrated with the built-in data file BOWEN.DAT
(stored in the Dataplot auxiliary directory). The following
Dataplot program
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READ BOWEN.DAT Y X1 X2 X3 ANOVA Y X1 X2 X3 . LET TAG = X2 + 2*(X3-1) CHARACTERS 1 1 2 2 LINES SOLID DOTTED SOLID DOTTED XTIC OFFSET 0.2 0.2 TITLE AUTOMATIC PLOT Y X1 TAG
Dataplot Output
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generated the following output
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**********************************
**********************************
** 3-WAY ANALYSIS OF VARIANCE **
**********************************
**********************************
NUMBER OF OBSERVATIONS = 8
NUMBER OF FACTORS = 3
NUMBER OF LEVELS FOR FACTOR 1 = 2
NUMBER OF LEVELS FOR FACTOR 2 = 2
NUMBER OF LEVELS FOR FACTOR 3 = 2
RESIDUAL STANDARD DEVIATION = 0.65340454102E+02
RESIDUAL DEGREES OF FREEDOM = 4
NO REPLICATION CASE
NUMBER OF DISTINCT CELLS = 8
****************
* ESTIMATION *
****************
GRAND MEAN = 0.18487500000E+03
GRAND STANDARD DEVIATION = 0.99256431580E+02
LEVEL-ID NI MEAN EFFECT SD(EFFECT)
--------------------------------------------------------------------
FACTOR 1-- -1.00000 4. 167.75000 -17.12500 23.10134
-- 1.00000 4. 202.00000 17.12500 23.10134
FACTOR 2-- -1.00000 4. 107.75000 -77.12500 23.10134
-- 1.00000 4. 262.00000 77.12500 23.10134
FACTOR 3-- -1.00000 4. 169.25000 -15.62500 23.10134
-- 1.00000 4. 200.50000 15.62500 23.10134
MODEL RESIDUAL STANDARD DEVIATION
-------------------------------------------------------
CONSTANT ONLY-- 99.2564315796
CONSTANT & FACTOR 1 ONLY-- 105.3697891235
CONSTANT & FACTOR 2 ONLY-- 59.6891250610
CONSTANT & FACTOR 3 ONLY-- 105.6801376343
CONSTANT & ALL 3 FACTORS -- 65.3404541016
*************
* TESTING *
*************
NUM. LEVELS F STAT. F CDF
------------------------------------------------
FACTOR 1-- 2 0.54952424765 50.033%
FACTOR 2-- 2 11.14592266083 97.113%
FACTOR 3-- 2 0.45747327805 46.410%
RESIDUAL STANDARD DEVIATION = 65.34045410156
RESIDUAL DEGREES OF FREEDOM = 4
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Date created: 06/05/2001 | ||