Analysis Using SPSS  

To test the significance of treatment combinations, identification of best treatment combination, to compare treatment combinations with and without farmyard manure(FYM) and also to compare the treatments with and without phosphorus solublizing bacteria (PSB), the analysis has to be performed on treatment combinations.Therefore the three factor treatment combinations are recoded as:

 Main Procedure is:  

Start →All Programs → SPSS for Windows → SPSS 15.0/ SPSS13.0/ SPSS10.0 (based on the version available on your machine) → Enter data in Data Editor → Analyze → GLM → Univariate → yield → [puts yield under Dependent list: ] → REP → [puts REP under Fixed Factor(s): ]   FYM → [put FYM under Fixed Factor(s):]  P → [puts P under Fixed Factor(s):] PSB → [puts PSB under Fixed Factor(s):] Continue → Model... [Opens Model dialogue box] → Custom → Build Term(s) → Main effects →   [puts FYM, P and PSB under Model:] → Interaction → [puts FYM*P FYM*PSB P*PSB and FYM*P*PSB under Model:] → Run All.

For performing analysis, input the data in the following format. 

{Here the Replication is termed as REP, three factors as FYM, P and PSB and treatment as TRT. It may, however, be noted that one can retain the same name or can code in any other fashion}.

Note: If one is interested in answering first two questions, then there is no need of recoding the treatment combinations and adding the variable TRT in the variable.

 Following are the brief description of the steps along with screen shots.

·         Open Data editor: Start → All Programs → SPSS for Windows → SPSS 15.0/ SPSS13.0/ SPSS10.0

·         Enter data in SPSS Data Editor. There are two views in SPSS Data Editor. In variable view, one can define the name of variables and variable type string or numeric and data view gives the spreadsheet in which data pertaining to variables may be entered in respective columns. In the present case, we enter data in numeric format.

·         Once the data entry is complete, Choose Analyze from the Menu Bar. Now select Analyze → General linear Model → Univariate.

·         This selection displays the following screen.

·         Select yield and send it to the Dependent Variable box; REP, FYM, P and PSB may be selected for Fixed Factor(s) box. After doing these the dialog box looks like this

·         For the Interactions select Model in the Univariate dialog box i.e. → Model... [Opens Model dialogue box] → Interaction→ FYM → P → [puts FYM*P under Model:].Similarly FYM*PSB, P*PSB and FYM*P*PSB can also be put under model.

      This selection displays the following screen.

·         Click Continue to return to the Univariate dialog box.

·         Alternatively, all possible pair wise treatment comparisons can be performed using the Button Options on the dialogue box. A click on Button Options, gives the option for estimated marginal means and display means for. From the left hand box, take the effect treatment in the Display means for. Then check the box Compare main effects and then there are 3 options for confidence interval adjustment viz. LSD(none), Bonferrnoni and Sidak. Any one of these 3 options can be selected. Default option is LSD(None). 

       A screen shot for these options is 

·Click Continue to return to the Univariate dialog box.

• Click OK.

This, however, gives comparisons of single factor level means and provides only the means for 2 factor level combinations and 3-factor level combinations. For 2-factor and 3-factor level combinations pairwise comparisons or post hoc comparisons cannot be performed using SPSS. 

For testing the significance of treatment combination, identification of best treatment combination and for contrast analysis use the following steps:

·         Choose Analyze from the Menu Bar. Now select Analyze → General linear Model → Univariate. Select yield and send it to the Dependent Variable box; REP and TRT to the Fixed Factor(s) box.

• Select Model in the Univariate dialog box i.e. → Model... [Opens Model dialogue box]. Put REP and TRT under the model for main effects

·    Click  Continue to return to the Univariate dialog box

    ·    For all possible pair wise treatment comparisons use the Button Options on the dialogue box. A click on Button Options, gives the option for          estimated marginal means and display means for. From the left hand box, take the effect treatment in the Display means for. Then check the box Compare main effects and then there are 3 options for confidence interval adjustment viz. LSD(none), Bonferrnoni and Sidak. Any one of these 3 options can be selected. Default option is LSD(None). 

             ·   A screen shot for these options is

       ·  Click Paste in the Univariate Dialogue Box to get the commands in the syntax editor.

           Hear define the contrast as

UNIANOVA

  Yield  BY REP TRT

  /METHOD = SSTYPE(3)

  /INTERCEPT = INCLUDE

  /EMMEANS = TABLES(TRT) COMPARE ADJ(LSD)

  /PRINT = DESCRIPTIVE

  /CRITERIA = ALPHA(.05)

/LMATRIX '1 2 3 4 5 6 vs 7 8 9 10 11 12' TRT 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1;

/LMATRIX'1 3 5 7 9 11 vs 2 4 6 8 10 12' TRT 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1;

  /DESIGN = REP TRT .

To answer all the questions 1 to 5, the following syntax may be used after creating the data file.

UNIANOVA

  Yield  BY REP FYM P PSB

  /METHOD = SSTYPE(3)

  /INTERCEPT = INCLUDE

  /EMMEANS = TABLES(FYM) COMPARE ADJ(LSD)

  /EMMEANS = TABLES(P) COMPARE ADJ(LSD)

  /EMMEANS = TABLES(FYM*P)

  /EMMEANS = TABLES(PSB) COMPARE ADJ(LSD)

  /EMMEANS = TABLES(FYM*PSB)

  /EMMEANS = TABLES(P*PSB)

  /EMMEANS = TABLES(FYM*P*PSB)

  /CRITERIA = ALPHA(.05)

  /DESIGN = REP FYM P FYM*P PSB FYM*PSB P*PSB FYM*P*PSB .

UNIANOVA

  Yield  BY REP TRT

  /METHOD = SSTYPE(3)

  /INTERCEPT = INCLUDE

  /EMMEANS = TABLES(TRT) COMPARE ADJ(LSD)

  /PRINT = DESCRIPTIVE

  /CRITERIA = ALPHA(.05)

/LMATRIX '1 2 3 4 5 6 vs 7 8 9 10 11 12' TRT 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1;

/LMATRIX'1 3 5 7 9 11 vs 2 4 6 8 10 12' TRT 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1;

  /DESIGN = REP TRT .