Developing crop descriptor lists - Bioversity International

iv BIOVERSITY INTERNATIONAL TECHNICAL BULLETIN SERIES NO. 13
6. Types of Scales 26
6.1 Scales for qualitative characteristics 27
6.1.1 Qualitative descriptors using nominal scale 28
6.1.2 Qualitative descriptors using ordinal scale 29
6.1.3 Qualitative descriptors using a binary scale 30
6.2 Scales for quantitative characteristics 30
6.2.1 Quantitative descriptors using a continuous scale 30
6.2.2 Quantitative descriptors using a discrete scale 31
7. Resolution, complexity and costs 33
7.1 Level of precision required 33
7.2 Complexity of the measurement or observation 34
7.3 Cost per measurement 34
8. Methods for collecting data 35
9. Experimental design 35
10. Scoring, coding and recording of descriptors 36
10.1 Recording heterogeneous data 38
11. Numeric versus alphanumeric coding schemes 41
MAKING DESCRIPTORS WORK 43
12. The development process 43
13. A few basic rules 43
14. Step-by-step checklist for defining descriptors 44
LOOKING FORWARD 47
BIBLIOGRAPHY AND FURTHER REFERENCES 49
Appendix I – Contributors, Coordinators and Reviewers 51
Appendix II – Standard reference sources 53
A2.1 References and standards used in developing
crop descriptor lists 53
A2.2 Base units – Système International d’Unités (SI) 54
Appendix III – FAO/IPGRI Multi-Crop Passport Descriptors 55
Appendix IV – List of standard descriptors for site
environment 59
Appendix V – Example Collecting form 70