Cluster analysis by manual method for educational purpose

Abstract

Cluster analysis is usually performed by using a computer. We tried manual cluster analysis without using a computer for educational purposes. Data used were DNA markers in random amplified polymorphic analysis of barley cultivars. Then number of DNA markers showing a different number of bands between the cultivars (different markers) was used as the distance. The pair with the fewest number of different markers was decided as the first cluster. Next, the difference between the mean number of different markers in the first cluster and the number in the other cultivars was calculated, and the second cluster with the least difference was decided. The same procedure was continued to decide the following clusters. Two-rowed and six-rowed barley cultivars with different origins showed a satisfactory dendrogram. Computer analysis gave the same result. This method can be easily understood and has a good educational effect.