Principles of Plant Genetics and Breeding

Purpose and expected outcomes
Statistics is indispensable in plant breeding. Breeders conduct the bulk of their work in the field under variable
environmental conditions that tend to mask real effects. Further, plant breeders often handle large amounts of
data that need to be summarized in order to facilitate sound decision-making. Computer software of all kinds is
available for use in plant breeding. The critical first thing is to know what statistical procedure to use to address a
specific problem. After studying this chapter, the student should be able to:
1 Describe the role of statistics in plant breeding.
2 Discuss the measures of central tendency.
3 Discuss the measures of dispersion.
4 Discuss the measures of association.
5 Discuss the method of analysis of variance.
6 Discuss multivariate analyses in plant breeding.
7 Discuss the concept of path analysis.
Role of statistics in plant breeding
The development of statistics arose out of a need to
assist researchers in those areas where the laws of cause
and effect are not apparent to the observer, and where
an objective approach is needed. Plant breeders use
statistics to design studies, analyze results, and draw sound
conclusions. The role of statistics in plant breeding may
be summarized in three key applications as follows:
1 To obtain a descriptive summary of the sample.
Research data are often large, requiring some mathematical
reduction to expose hidden trends for easy
interpretation. The values obtained from such descriptive
analysis are sometimes called summary statistics.
9
Common statistical
methods in plant
breeding
2 To provide a means of statistical inference. The
key purpose of collecting data in research is to enable
the researcher to draw some kind of inference about a
certain characteristic of the population from which
the data were drawn. To do this, the values obtained
about the sample are used.
3 Comparison. Often, the researcher has multiple sets
of experimental data and needs to know whether
they represent significantly different populations of
measurement. Another way of putting this is that the
objectives of statistics are the estimation of population
parameters and the testing of hypotheses about
the parameters.
Statistical methods used in plant breeding can range
from the simple and straightforward such as arithmetic