Phenotype (or phenotypic value) is the performance of a trait in interest, which can be observed in the field and then used in estimating the unknown genotypic value (or the phenotypic mean). In this chapter, we introduced statistical approaches to analyze three types of phenotypic observation, i.e., (1) replicated observations of one genotype in one environment, (2) replicated observations of multiple genotypes in one environment, and (3) replicated observations of multiple genotypes in multiple environments. The principle of analysis of variance (ANOVA) was applied on each kind of phenotypic data. From the results of ANOVA, we can further estimate genotypic value, genetic effects, variance components, heritability, etc., which can be further used in genetic studies and breeding applications. In the end, we present a computer tool implemented in the integrated genetic software QTL IciMapping, which includes the biometrical approaches introduced in this chapter and can be readily used in phenotyping complex traits.