Randomized Block Design
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چکیده
Example It is common in nutrition studies to compare diets by feeding them to newly weaned male rats and measuring the weight gained by the rats over a 28-day period. The initial weight of the rats is an extraneous factor that is especially important as an influence on weight gain. Rather than randomly assign 10 rats to each diet, we first divide the animals into 10 groups of 3 rats each based on weight. Three lightest rats form the first group, the next lightest three form the second group, and so on, with the tenth group consisting of the three heaviest rats. These groups of rats of similar weight are called blocks. Now we randomly assign one rat from each block to each diet. This design is used to screen out the effects of the extraneous factor, initial weight.
منابع مشابه
NAG Fortran Library Routine Document G04BBF
In a completely randomized design the experimental material is divided into a number of units, or plots, to which a treatment can be applied. In a randomized block design the units are grouped into blocks so that the variation within blocks is less than the variation between blocks. If every treatment is applied to one plot in each block it is a complete block design. If there are fewer plots p...
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