Essay --

Part I 1. How many independent variables are in a 4X6 factorial design? How many conditions are in this design? There are 4 and 6 independent variables, and 24 conditions for this design. 2. What is the difference between a cell mean and the means used to interpret a main effect? The main effect is used to interpret the differences in means over levels of one factor collapsed over levels of the other factor (Jackson, 2012). However, the cell mean is used to interpret is used with models that include three-way interactions. In addition, a cell means is used with mixed procedures (Jackson, 2012). 3. What is the difference between a complete factorial design and an incomplete factorial design? The complete factorial design consists of all combinations of all factor-levels of each factor; and it can estimate all factors and their interactions (Collins, Dziak, & Li, 2009; Jackson, 2012). In addition, the fixed-level designs may be calculated (Collins, Dziak, & Li, 2009). For example, a two-level factor, a three-level factor, and a four-level factor has 2 x 3 x 4 = 24 runs. The incomplete factorial design some of the cells are intentionally left empty, where participants will not be assigned to those combinations of factors. It is most likely to be used in a controlled group (Trochim, 2000; Jackson, 2012). Therefore, the research can evaluate relative treatment comparisons within a single study and be able to determine the effect of different treatment combinations (Trochim, 2000; Jackson, 2012). 4. Explain the difference between a two-way ANOVA and a three-way ANOVA? A one-way ANOVA is used when the research wants to evaluate the differences between variables (Kirk, 1995; Jackson, 2012). For example, a study may evaluate the dif... ...her factor (Trochim & Donnelly, 2008). How does a covariate reduce noise? An ANCOVA design is a noise-reducing experimental design can adjusts posttest scores for variability on the covariate pretest. Covariates are the variables you adjust for, where the effect is going to be removed. Any continuous variable can be used as the covariate; however, the pretest is usually best (Trochim & Donnelly, 2008). Describe and explain three trade-offs present in experiments. Schank and Koehnle (2009) argued that the three trade-offs present in experiments are the inevitable in any decisions including blocking or to standardize conditions in experiments. The interpretation of multiple tests of a hypothesis is clarified. Experiments with large samples raise the possibility of small, but statistically significant, biases even after randomization of treatments (Wiley, 2009).