Ronald Fisher's ANOVA (Analysis of Variance) is a statistical method used to compare the means of three or more groups to determine if at least one group mean is significantly different from the others. Developed by Ronald A. Fisher in the early 20th century, this technique helps researchers analyze the impact of one or more independent variables on a dependent variable. ANOVA works by partitioning the total variance observed in the data into variance within groups and variance between groups. If the variance between groups is significantly larger than the variance within groups, it suggests that the group means are not all equal, indicating a potential effect of the independent variable.