Stats 3520 Example: Single Factor Experiment One way to repair serious wounds is to insert some material as a scaffold for the body's repair cells to use as a template for new tissue. Scaffolds made from extracellular material (ECM) are particularly promising for this purpose. Because they are made from biological material, they serve as an effective scaffold and are then resorbed. Unlike biological material that includes cells, however, they don't trigger tissue rejection reactions in the body. One study compared 6 types of scaffold material. Three of these were ECM's and the other three were made of inert materials. There were three mice used per scaffold type. The response measure was the percent of glucose phosphated isomerase (Gpi) cells in the region of the wound. A large value is good, indicating that there are many bone marrow cells sent by the body to repair the tissue. Material Gpi (%) ---------------------- ECM1 55 70 70 ECM2 60 65 65 ECM3 75 70 75 MAT1 20 25 25 MAT2 5 10 5 MAT3 10 15 10 Does the type of material affect the percent of Gpi cells around the wound? If so, what materials seem to be the best to use? ############################################## On the next page we find the SAS commands that can be used to study this data (we will have a class soon in the lab to get some SAS practice). title 'Single Factor Experiment: Wound Healing'; options linesize=79; data wounds; infile 'gpi.dat'; # These lines read in data from a file input Material Gpi; # Tells SAS what variables are in each column PROC PRINT; # Prints the data PROC ANOVA; # ANOVA = Analysis of Variance CLASS Material; # Material is a factor (classification variable) MODEL Gpi = Material; # The model MEANS Material; # Find mean of gpi for each material PROC GLM; # GLM = General Linear Model CLASS Material; # For this example, will do basically MODEL Gpi = Material; # the same thing as ANOVA RUN; # Tells SAS to get to work %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% SAS output from these commands: Single Factor Experiment: Wound Healing 1 Obs Material Gpi 1 1 55 2 1 70 3 1 70 4 2 60 5 2 65 6 2 65 7 3 75 8 3 70 9 3 75 10 4 20 11 4 25 12 4 25 13 5 5 14 5 10 15 5 5 16 6 10 17 6 15 18 6 10 Single Factor Experiment: Wound Healing 2 The ANOVA Procedure Class Level Information Class Levels Values Material 6 1 2 3 4 5 6 Number of observations 18 Single Factor Experiment: Wound Healing 3 The ANOVA Procedure Dependent Variable: Gpi Sum of Source DF Squares Mean Square F Value Pr > F Model 5 13411.11111 2682.22222 137.94 <.0001 Error 12 233.33333 19.44444 Corrected Total 17 13644.44444 R-Square Coeff Var Root MSE Gpi Mean 0.982899 10.87295 4.409586 40.55556 Source DF Anova SS Mean Square F Value Pr > F Material 5 13411.11111 2682.22222 137.94 <.0001 Single Factor Experiment: Wound Healing 4 The ANOVA Procedure Level of -------------Gpi------------- Material N Mean Std Dev 1 3 65.0000000 8.66025404 2 3 63.3333333 2.88675135 3 3 73.3333333 2.88675135 4 3 23.3333333 2.88675135 5 3 6.6666667 2.88675135 6 3 11.6666667 2.88675135 Single Factor Experiment: Wound Healing 5 The GLM Procedure Class Level Information Class Levels Values Material 6 1 2 3 4 5 6 Number of observations 18 Single Factor Experiment: Wound Healing 6 The GLM Procedure Dependent Variable: Gpi Sum of Source DF Squares Mean Square F Value Pr > F Model 5 13411.11111 2682.22222 137.94 <.0001 Error 12 233.33333 19.44444 Corrected Total 17 13644.44444 R-Square Coeff Var Root MSE Gpi Mean 0.982899 10.87295 4.409586 40.55556 Source DF Type I SS Mean Square F Value Pr > F Material 5 13411.11111 2682.22222 137.94 <.0001 Source DF Type III SS Mean Square F Value Pr > F Material 5 13411.11111 2682.22222 137.94 <.0001