Statistical Techniques IIEXST7015Experimental Design Identification02b_Daily Design Identification 1Experimental Design IdentificationTo correctly design an experiment, or to analyze a designed experiment, you must be able to look at a design situation and correctly assess the salient aspects of the design. I will ask you to identify the design, the treatment variable, dependent variable, degrees of freedom error, experimental unit, sampling unit (if any), and if the treatment is fixed or random. 02b_Daily Design Identification 2Design Ident (continued)To begin with, determine what the investigators are trying to do and what they plan to measure. What is the Objective of the study?Specifically, what hypotheses are to be tested? What is the variable of interest? What unit is the treatment applied to?What, exactly, is the unit measured? 02b_Daily Design Identification 3Design Ident (continued)Suppose an investigator wants to compare the oxygen levels in seven predefined "habitats" in the Louisiana marsh. He will randomly select and sample 4 sites in each habitat. One oxygen measurement is made at each site. What are the treatments? What is the investigator interested in comparing?Treatments? Habitats (t=7) 02b_Daily Design Identification 4Design Ident (continued)Are there any sources of variation that should be recognized, but which are not important to the investigator. For example, did he replicate the experiment in several locations along the coast? Blocks? Apparently none. What sampling unit is associated with the treatment? What unit was the treatment applied to or what was sampled for each treatment (habitat)?Experimental unit? A site (s=4) 02b_Daily Design Identification 5Design Ident (continued)What is the sampling unit at each site? In this case it is a water sample on which oxygen is measured. Since there is only a single sample at each site we can consider each sample to represent the site. Sampling units. A siteIf there were multiple samples taken at each site these would be the sampling units. These in turn can be split into sub-sampling units. 02b_Daily Design Identification 6Design Ident (continued)Is that all? There are other issues, not all of which we have covered. Are the treatments fixed or random? Is the design balanced? Are there any particular hypothesis tests of interest (contrasts)? Are the treatment levels quantitative?Any other special post ANOVA applications? 02b_Daily Design Identification 7Daily Design ObjectivesThe topic of Design will be discussed in the second half of the course. For the moment our objective is only to learn to identify the components of an experiment. Therefore, I will put a design description on the Internet and each class period ask you to have looked at it and to be prepared to answer the following questions. 02b_Daily Design Identification 8Daily Design (continued)Questions I will ask:What is the treatment arrangement for this experiment?(a) single factor (b) factorial (c) nestedWhat is the experimental design for this experiment? (a) CRD (b) RBD (c) LSD (e) Split-plot (d) Repeated Measures02b_Daily Design Identification 9Daily Design (continued)Does it seem more likely that the treatments are fixed or random?(a) fixed (b) randomWhat is the experimental unit for this experiment?(a) site (b) habitat (c) water sample (d) oxygenWhat is the sampling unit for this experiment?(a) site (b) habitat (c) water sample (d) oxygen02b_Daily Design Identification 10Daily Design (continued)What is the dependent variable for this experiment?(a) site (b) habitat (c) water sample (d) oxygenIf there are blocks in the design, what are the blocks? (a) site (b) habitat (c) water sample (d) oxygenHow many degrees of freedom are available for testing the treatments? Enter the correct value here: _______02b_Daily Design Identification 11Daily Design (continued)For the little experiment discussed the source table is:Source d.f.Treatment 6Error 21Total 2702b_Daily Design Identification