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Zero Residual Sum of Square in ANOVA

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 Summary: This blog explains case when the residual sum of square is zero for two way ANOVA (RBD Design in terms of DoE). A sample data set is shared for detailed explanation. The goal is to share the observation.  Reading time 5 mins Introduction In the field of Design of Experiments (DoE) , the Randomized Block Design (RBD) is a commonly used layout where treatments are tested across blocks or replications. Typically, the ANOVA table in RBD presents some residual (error) variation that captures the unexplained variance. However, there are rare instances when the residual sum of squares (SS) turns out to be zero . In this blog, we demonstrate one such case using a small dataset and provide insights into why this occurs , backed by observations. Data set used in demonstration: The data is of 6 treatments T1, T2, T3, T4, T5 and T6 with three replications R1, R2 and R3. When we perform two way ANOVA the results is shown below: As we can observe that difference between R1...