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Investigating the effects of season and adult density on egg production in Siphonaria diemenensis through a factorial analysis of variance. The study explores the interaction between factors and their impact on productivity. Null hypotheses are tested to determine treatment effects.
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Orthogonal • Is the property that every level of one factor is present in the experiment in combination with every level of the other factor
Effects of season (winter/spring and summer/fall) and adult density (8,15, 30 y 45 animales/225 cm2) on egg production of Siphonariadiemenensis
Spring-30 Summer- 15 Summer- 45 Summer- 30 Spring-8 Spring-15 Summer- 15 Summer- 8 Spring-15 Summer- 8 Spring-40 Summer- 45 Spring-40 Summer- 45 Spring-30 Summer- 30 Spring-8 Spring-40 Spring-15 Summer- 15 Spring-8 Summer- 8 Summer- 30 Spring-30
Null hypothesis • No effects of treatment A • No effects of treatment B • No effects of the interaction
Data Density
Consider the entire analysis as though it were a single factor factorial experiment with ab experimental treatments
Now start again and ignore any differences among the data that might be due to factor B. Equivalent to a single-factor analysis of variance of means of the levels of factor A (with a treatments each replicated bn times) A symmetrical argument can be made to analyze the data as a single factor B
Not all the differences among means of the ab combinations of treatments have been accounted for by the two single factor analyses • The remaining differences can be identified empirically as • SS among all treatments- SS factorA- SS factorB= ΣiaΣjb(Xij-Xi-Xj+X)2
Expected mean squares for test of null hypothesis for twofactorial analysis (A fixed, B fixed)
Expected mean squares for test of null hypothesis for twofactorial analysis (A random, B random)