Dataplot Solution to a Data Analysis Problem


Dataplot Solution to the Data Analysis Problem
Problem Setup	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.
Dataplot Program	This is demonstrated with the built-in data file BOWEN.DAT (stored in the Dataplot auxiliary directory). The following Dataplot program SKIP 25 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	generated the following output ******************************** ****************************** 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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Dataplot Solution to the Data Analysis Problem