Finals Flashcards
The treatments are assigned completely at random so that each experimental unit has the same chance of receiving any one treatment.
Completely Randomized Design
It is considered a ___________ ______ if there is a difference among experimental units receiving the same treatment.
Experimental error
the CRD is only appropriate for
experiments with __________ _______ ____, such as laboratory experiments, where
environmental effects are relatively easy to control.
homogenous experimental units
T/F. field experiments, where there is generally large variation among experimental plots, in such environmental factors as soil, the CRD is oftenly used.
False, CRD is RARELY used
the simplest type of design to use.
Completely randomized design
What is the most important requirement for the use of the CRD design?
homogeneity of experimental units.
What are the methods of Increasing Accuracy of Experiments in CRD
- Increase the size of the experiment by increasing the number of replicates.
- Refine the experimental technique.
- Handle experimental material so that the effects of variability are reduced.
T/F. In CRD, data should be collected by the same person using the same units.
True
What is the Step 1 in CRD?
Determine the total number of experimental plots (n) as the product of
number of treatments (t) and the number of replications (r);
What is the Step 2 in CRD?
Assign a plot number to each experimental plot in any convenient manner;
What is the Step 3 in CRD?
Randomly assign the treatments to the
experimental plots
These are factors beyond control (extraneous factors)
Experimental error
Test hypotheses for statistical significance of comparisons of treatment means, where “treatment” or “factor” is the characteristic that distinguishes the populations.
ANOVA
The one-way ANOVA is useful when we want to compare the effect of _______ _____ __ ___ ______and we have multiple observations at each level.
multiple levels of one factor
T/F. The treatment difference is said to be real if the treatment variation is sufficiently smaller than the experimental error.
False. The treatment variation should be larger than the experimental error.
a ___________ _ ____ in the analysis of variance indicates the failure of the experiment to detect any difference among treatments.
nonsignificant F test
What does the CV indicate?
degree of precision
T/F. The higher the cv value, the lower is the reliability of the experiment.
True
Example studies for CRD-unequal replications.
- Animal feeding experiments where the number of animals for each breed is not the same.
- Experiments for comparing body length of different species of insect caught in an insect trap.
T/F. As a general guideline, the F value should be computed only when the error d.f. is six and below.
False, six or more.
It is highly significant if the computed F is
> Tabular F at 1% level of significance
It is significant if the Tabular F at 1% of significance is
≥ Computed F at 5% level of significance
It is not significant if the computed F is
less than or equal to Tabular F at 5% level of significance
one of the most widely used experimental designs in agricultural research.
RANDOMIZED COMPLETE BLOCK DESIGN
especially suited for field experiments where the number of treatments is not large and the experimental area has a predictable productivity gradient.
RCBD
The primary distinguishing feature of the RCBD design is _________ __ _____ __ ____ ____, each of which contains all
the treatments.
presence of blocks of equal size
In RCBD what is used to isolate major sources of variation?
Blocking or stratification
In this design there is an equal number of replications.
RCBD
T/F. In RCBD, each block is selected so that it is as uniform in conditions as possible and each block contains all the treatments assigned at random.
True
In RCBD, the number of blocks corresponds
to the number of replications of treatments.
In all stages of the experiment, what is the main objective?
To keep the experimental error as small as possible
T/F. In RCBD, all units that go in groups should be different. Hence, changes can be made between groups only.
False, all units in groups should be similar.
It is suitable in on-farm trials because the experimental error due to heterogeneity in site conditions is reduced through blocking.
RCBD
What are the advantages of RCBD?
- Any number of treatments and replication can be allowed as long as the area is homogenous.
- Statistical analysis is straightforward.
- very effective in reducing experimental error by removing one source of variation.
What is the disadvantage of RCBD?
It is not suitable doe large numbers of treatments, because the homogeneity of the block is difficult
T/F. At least two blocks are required to run an experiment in RCBD.
TRUE
T/F. The error degrees of freedom being recommended should exceed 10, but some analysts accept 6.
True
T/F In RCBD, field experiments using trees, the number of blocks is from 2 to 5.
False, 3-5
Steps in Making a RCBD lay-out
- The experimental material is divided into blocks. Each block constitutes a replication of the treatment.
- For an effective blocking technique, direction of site variation should be used as basis of blocking as well
as the shape an orientation of each block. - The treatments are assigned at random to the units in
each block similar to that of CRD, however, randomization is restricted within each block only.
What is the primary purpose of blocking?
to reduce experimental error by eliminating the contribution of known sources of among experimental units.
This is done by grouping the experimental units into blocks
such that variability within each block is minimized and variability among blocks is maximized.
BLOCKING TECHNIQUE
blocking is most effective when
experimental area has a predictable pattern of variability
What are two important decisions that have to be made in arriving at an appropriate and effective blocking technique?
- The selection of the source of variability to be used as the basis for blocking.
- The selection of the block shape and orientation.
What are three sources of variability in a RCB design?
treatment,
replication (or block)
experimental error
we will reject the null hypothesis if
the computed F is
greater than the tabular value of F,
otherwise, we will accept H0.
factor that is hard to change/vary
Whole plot
factor that is easy to change/vary
Sub plot
Steps in Split plot design
- Make the layout
- Layout the subplots within each whole plot, and assign the subplot treatments guided by randomization result
- Gather the data and tabulate
- Prepare Replication x Whole Plot Data Table
- Prepare Whole Plot (Stem sections) x Sub-Plot (Rooting hormones) Data Table\
- Prepare ANOVA Table
- Compute for correction factor and sum of squares
It provides the glue that holds the research project together.
Research design
Backbone of the research protocol
Research design
What is the difference between research design and research method?
The RD is the plan and the RM is the strategy used to implement that plan.
