III EXPLORATORY TRIALS


Superimposed Trials 30
The 2" Factorial Trial 32
 Interpretation of results 36
 Comments on reducing the size of the trial 37
The "Plus" Trial 37
The "Minus" Trial 41

IV SITE-SPECIFIC TRIALS 45

Basic Considerations 46
 Plot size 46
 Variety evaluation 46
 Crop associations 47
 Plant nutrition 48
 Plant protection 49
Analysis of Results 49


V RESEARCHER-MANAGED REGIONAL TRIALS:
 AGRONOMIC EVALUATION 57

Design and Methodology 58
 Experimental designs 59
 Number of replications 59
 Number of treatments 59
 Control treatments 60
 Kinds of treatments 60
 Selection of sites 62
 Complexity 63
 Replication over years 63
Combining Data over Sites 63
 Combined analysis of variance 64



 VI RESEARCHER-MANAGED REGIONAL TRIALS:
 SOCIOECONOMIC EVALUATION 73

Choice of Evaluation Criteria 74
 Labor input as an evaluation criterion 75
 Cash as an evaluation criterion 78
Response Surfaces 79
 What they are 79
 Representative forms 79
 Economic analysis 81
Methods of Obtaining Response Surfaces 85
 Simple regression--visiographic 85
 Simple regression--least squares 92