SCHOOL OF BIOMEDICAL SCIENCES BSC
BIOMEDICAL SCIENCES YEAR IV
NAME: CHAMA KABASO
COMPUTER NO#: 201912010459
COURSE: EPIDEMIOLOGY
LECTURER: MR MODERN NTALASHA
ASSIGNMENT NO#: 2
TASK:
DUE DATE: 25th August , 2021
Q1 how does experimental studies differ from descriptive studies
Q2.what value do they have in epidemiology
Q3. What principles must the investigators have in order to properly carry out an experimental
study
Q1 how does experimental studies differ from descriptive studies
Q2.what value do they have in epidemiology
Experiments are conducted to be able to predict phenomenons. Typically, an experiment
is constructed to be able to explain some kind of causation. Experimental research is
important to society - it helps us to improve our everyday lives.
Properly executed experimental studies provide the strongest empirical evidence. The
randomization also provides a better foundation for statistical procedures than do
observational studies.
It provides researchers with a high level of control.
By being able to isolate specific variables, it becomes possible to determine if a potential
outcome is viable. Each variable can be controlled on its own or in different
combinations to study what possible outcomes are available for a product, theory, or idea
as well. This provides a tremendous advantage in an ability to find accurate results.
There is no limit to the subject matter or industry involved.
Experimental research is not limited to a specific industry or type of idea. It can be used
in a wide variety of situations. Teachers might use experimental research to determine if
a new method of teaching or a new curriculum is better than an older system.
Pharmaceutical companies use experimental research to determine the viability of a new
product.
Experimental research provides conclusions that are specific
Because experimental research provides such a high level of control, it can produce
results that are specific and relevant with consistency. It is possible to determine success
or failure, making it possible to understand the validity of a product, theory, or idea in a
much shorter amount of time compared to other verification methods. You know the
outcome of the research because you bring the variable to its conclusion.
The results of experimental research can be duplicated.
Experimental research is straightforward, basic form of research that allows for its
duplication when the same variables are controlled by others. This helps to promote the
validity of a concept for products, ideas, and theories. This allows anyone to be able to
check and verify published results, which often allows for better results to be achieved,
because the exact steps can produce the exact results
Natural settings can be replicated with faster speeds.
When conducting research within a laboratory environment, it becomes possible to
replicate conditions that could take a long time so that the variables can be tested
appropriately. This allows researchers to have a greater control of the extraneous
variables which may exist as well, limiting the unpredictability of nature as each variable
is being carefully studied.
Experimental research allows cause and effect to be determined.
The manipulation of variables allows for researchers to be able to look at various cause-
and-effect relationships that a product, theory, or idea can produce. It is a process which
allows researchers to dig deeper into what is possible, showing how the various variable
relationships can provide specific benefits. In return, a greater understanding of the
specifics within the research can be understood, even if an understanding of why that
relationship is present isn’t presented to the researcher.
It can be combined with other research methods.
This allows experimental research to be able to provide the scientific rigor that may be
needed for the results to stand on their own. It provides the possibility of determining
what may be best for a specific demographic or population while also offering a better
transference than anecdotal research can typically provide
Q3. What principles must the investigators have in order to properly carry out an experimental
study
There are three basic principles behind any experimental study
Randomisation: the random allocation of treatments to the experimental units.
Randomize to avoid confounding between treatment effects and other unknown effects.
Replication: the repetition of a treatment within an experiment allows:
To quantify the natural variation between experimental units.
To increase accuracy of estimated effects.
Local control: by controlling as much as possible the conditions in the experiment. A classical
example is the grouping of similar experimental units in blocks
1) Randomization. The first principle of an experimental design is randomization, which is a
random process of assigning treatments to the experimental units. The random process implies
that every possible allotment of treatments has the same probability. An experimental unit is the
smallest division of the experimental material, and a treatment means an experimental condition
whose effect is to be measured and compared. The purpose of randomization is to remove bias
and other sources of extraneous variation which are not controllable. Another advantage of
randomization (accompanied by replication) is that it forms the basis of any valid statistical test.
Hence, the treatments must be assigned at random to the experimental units. Randomization is
usually done by drawing numbered cards from a well-shuffled pack of cards, by drawing
numbered balls from a well-shaken container or by using tables of random numbers.
(2) Replication. The second principle of an experimental design is replication, which is a
repetition of the basic experiment. In other words, it is a complete run for all the treatments to be
tested in the experiment. In all experiments, some kind of variation is introduced because of the
fact that the experimental units such as individuals or plots of land in agricultural experiments
cannot be physically identical. This type of variation can be removed by using a number of
experimental units. We therefore perform the experiment more than once, i.e., we repeat the
basic experiment. An individual repetition is called a replicate. The number, the shape and the
size of replicates depend upon the nature of the experimental material. A replication is used to:
(i) Secure a more accurate estimate of the experimental error, a term which represents the
differences that would be observed if the same treatments were applied several times to the same
experimental units;
(ii) Decrease the experimental error and thereby increase precision, which is a measure of the
variability of the experimental error; and
(iii) Obtain a more precise estimate of the mean effect of a treatment,
since σ2y¯¯¯=σ2nσ2y¯=σ2n, where nn denotes the number of replications
.
(3) Local Control. It has been observed that all extraneous sources of variation are not removed
by randomization and replication. This necessitates a refinement of the experimental technique.
In other words, we need to choose a design in such a manner that all extraneous sources of
variation are brought under control. For this purpose, we make use of local control, a term
referring to the amount of balancing, blocking and grouping of the experimental units. Balancing
means that the treatments should he assigned to the experimental units in such a way that the
result is a balanced arrangement of the treatments. Blocking means that like experimental units
should be collected together to form a relatively homogeneous group. A block is also a replicate.
The main purpose of the principle of local control is to increase the efficiency of an experimental
design by decreasing the experimental error. The point to remember here is that the term local
control should not be confused with the word control. The word control in experimental design is
used for a treatment which does not receive any treatment when we need to find out the
effectiveness of other treatments through comparison.
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