NUMBER 21 STATISTICS identify the particular feature that de

NUMBER 21 STATISTICS

identify the particular feature that defines each of the following experimental design, and list the specific advantages provided by the feature you identify.

a) factorial design

b) randomized block design

c) completely randomized design.

Solution

(a)

A two-way design enables us to examine the joint (or interaction) effect of the independent variables on the dependent variable. An interaction means that the effect of one independent variable has on a dependent variable is not the same for all levels of the other independent variable. We cannot get this information by running separate one-way analyses. Factorial design can lead to more powerful test by reducing the error (within cell) variance. This point will appear clearly when will compare the result of one-way analyses with the results of a twoway analyses or t-tests.

(b)

Advantages of randomized complete block designs 1. Complete flexibility. Can have any number of treatments and blocks. 2. Provides more accurate results than the completely randomized design due to grouping. 3. Relatively easy statistical analysis even with missing data. 4. Allows calculation of unbiased error for specific treatments.

(c)Advantages of Completely Randomized Design are as follows:

1.CRD is flexible because it can be done even in a limited number of experimental subjects however equal number of subjects for each treatment is encourage.2Statistical analysis is simple and easy

3.Statistical analysis is manageable even though some of the experimental subjects or treatments are lacking