BookmarkSubscribeRSS Feed
🔒 This topic is solved and locked. Need further help from the community? Please sign in and ask a new question.
amarikow57
Obsidian | Level 7

My knowledge on two-way ANOVAs is a bit shaky so I'm hoping for some clarification. So it appears my overall model is significant (p < 0.0001). However, I am a bit confused why pressure is nonsignificant and temperature is significant in the Type III ANOVA table. Yet individual levels of pressure are significant and temperature 270 has no values. Are these the difference between main effects and simple effects?

Furthermore, I was going to look at pairwise comparisons, but it that wrong when there is no interaction? That is, I can't really control for temperature when comparing different pressure levels and vise versa.

 

Data

 

DATA DATA.Temp;
 input Pressure Temp Strength @@;
 datalines;
 120 250 9.60 120 260 11.28 120 270 9.00
 130 250 9.69 130 260 10.10 130 270 9.57
 140 250 8.43 140 260 11.01 140 270 9.03
 150 250 9.98 150 260 10.44 150 270 9.80
 ;
RUN;

 

 

Model Procedure

 

PROC GLM data = DATA.Temp plots = ALL;
 class pressure temp;
 model strength = pressure temp / clparm noint solution;
 means pressure temp / hovtest = Levene;
 lsmeans pressure temp / pdiff = all adjust = Tukey;
RUN;

Output

 

Source

DF

Sum of Squares

Mean Square

F Value

Pr > F

Model

6

1164.195417

194.032569

540.51

<.0001

Error

6

2.153883

0.358981

 

 

Uncorrected Total

12

1166.349300

 

 

 

Source

DF

Type III SS

Mean Square

F Value

Pr > F

Pressure

3

0.58069167

0.19356389

0.54

0.6727

Temp

2

4.65765000

2.32882500

6.49

0.0316

Parameter

Estimate

 

Standard
Error

t Value

Pr > |t|

95% Confidence Limits

Pressure  120

9.482500000

B

0.42366293

22.38

<.0001

8.445834157

10.519165843

Pressure  130

9.309166667

B

0.42366293

21.97

<.0001

8.272500824

10.345832510

Pressure  140

9.012500000

B

0.42366293

21.27

<.0001

7.975834157

10.049165843

Pressure  150

9.595833333

B

0.42366293

22.65

<.0001

8.559167490

10.632499176

Temp      250

0.075000000

B

0.42366293

0.18

0.8653

-0.961665843

1.111665843

Temp      260

1.357500000

B

0.42366293

3.20

0.0185

0.320834157

2.394165843

Temp      270

0.000000000

B

.

.

.

.

.

 

 

1 ACCEPTED SOLUTION

Accepted Solutions
PaigeMiller
Diamond | Level 26

The Type III test is testing to see if the levels of each variable are different from one another. So the levels of TEMP are different from one another, the levels of PRESSURE are not.

 

The parameter estimate tests are testing to see if the estimate is different from zero. So for PRESSURE, the estimates are different from zero.

--
Paige Miller

View solution in original post

1 REPLY 1
PaigeMiller
Diamond | Level 26

The Type III test is testing to see if the levels of each variable are different from one another. So the levels of TEMP are different from one another, the levels of PRESSURE are not.

 

The parameter estimate tests are testing to see if the estimate is different from zero. So for PRESSURE, the estimates are different from zero.

--
Paige Miller

sas-innovate-2024.png

Available on demand!

Missed SAS Innovate Las Vegas? Watch all the action for free! View the keynotes, general sessions and 22 breakouts on demand.

 

Register now!

What is ANOVA?

ANOVA, or Analysis Of Variance, is used to compare the averages or means of two or more populations to better understand how they differ. Watch this tutorial for more.

Find more tutorials on the SAS Users YouTube channel.

Discussion stats
  • 1 reply
  • 336 views
  • 1 like
  • 2 in conversation