Part 1 1. Explain the difference between the terms factors and treatments. Give an example

Within an experimental setting, the term factor which is also referred to as an independent variable is a variable that is explanatory and can usually be manipulated by the one conducting the experiment. Every factor typically has different values meaning that there are two or more levels for the factor. On the other hand, treatment can be defined as a combination or amalgamation of these factor levels. That is, it is a mixture of the different values of the independent variable (Heath, 2002).

2. What are some potential problems of a poor experimental design?

One of the potential problems of a poor experimental design is biasedness. This is largely for the reason that such a design fails overlooks and fails to take into consideration the rules of randomization and facilitates augmented experimental mistakes. In addition, this implies that there is the potential problem of validity and reliability of the research study or experiment.

3. Draw an outline of a randomized comparative experiment with five different treatment groups.

An example of a randomized comparative experiment can encompass the provision of two different kinds of treatment, including Vitamin C and Vitamin K. The subjects of the study are assigned in a random manner.

The following is an outline of a randomized comparative experiment with five different treatment groups:

Vitamin C

0 mg

40 mg

60 mg

80 mg

100 mg

Vitamin K

0 mg

20 mg

50 mg

70 mg

100 mg

4. Explain why it is important to use the following:

a) Randomization

Randomization takes into account the use of chance in the assigning process of experimental groups or subjects to treatments. The advantage of using randomization is that it avoids any bias in the practice of selection and guarantees that there is no inadvertent bias. In addition, it generates groups that are comparable and eradicates the source of bias within the assignment done to treatments (Laurel, 2003).

b) Replication

It is important to make use of replication in a study because it facilitates the use of enough or sufficient experimental units in every group in order that any differences in the treatment effects can be distinguished from the variances that exist between the groups (Laurel, 2003).

c) control groups

A control group is delineated as the group within a study that does undergo the treatment being examined by the researchers or experimenters and is thereafter employed as a standard to measure the manner in which other subjects being tested perform or respond.

5. Explain the meaning of the term block design. When is such a design appropriate?

In a block design randomized study, the person conducting the experiment categorized the subjects into smaller subgroups referred to as block, in the sense that the variability existing within these blocks is lesser as compared to the variability existing between these blocks. Subsequently, the subjects within every within every block or subgroup are randomly assigned to the different treatment conditions in the study (Laurel, 2003).

6. Explain what is meant by a matched pairs design. Give an example.

A matched pairs design is a distinctive case of a randomized block design. This design can solely be used at an instance where the experiment has solely two treatment conditions. Therefore, the participating subjects in the studies are categorized into pairs, on the basis of a kind of blocking variable. Subsequently, in every pair categorized, randomization...

Explain the meaning of the following terms:
a) Placebo

Within an experiment, the participants involve usually react in dissimilar manners subsequent to receiving treatments. A placebo is a treatment that is neutral that does not have any actual effect on the subject, despite the fact that the subject shows a positive response to such a treatment (Heath, 2002).

b) double-blind

In an experiment, double-blind takes into account a testing practice whose design is purposed to eradicate biased outcomes, in which the individuality of those obtaining a test treatment is hidden not just on the subjects but also the experiment administrators up to the point when the study is finished (Mitchell and Jolley, 2012).

c) Confounding

An experiment design that is confounding is one in which a number of treatment effects are appraised by the similar linear mixture or grouping of the experimental observations akin to a number of blocking effects. In this regard, there is confounding in both the blocking effect and the treatment effect (Mitchell and Jolley, 2012).

d) response

A designed experiment is deemed to be a controlled research study whereby one or more treatments are employed to subjects. The one conducting the experiment thereafter makes an observation of the effect of changing and fluctuating these treatments on a response variable. In other words, a response variable is considered to be the variable of interest within an experiment (Mitchell and Jolley, 2012).

Part 2

1. People who provide an answer to telephone surveys typically listen to an interviewer’s introductory remarks, and then decide if they want to continue or hang up. Suppose that a study made telephone calls to randomly selected households and asked about opinions for an upcoming election. To investigate responses, the interviewer sometimes gave her name, in others she identified the university she enrolled in, and in still others she identified both herself and her university. The study recorded the percentage of each group of interviews that was fully completed.

a) Is this telephone survey an example of an observational study or an experiment?

The key difference between an experiment and an observational study is that in the latter, the experimenter does not have any control over the variables whereas an experiment is an approach encompassing the application of treatments to a group and having records of such effects. In this particular case, the telephone survey is an example of an observational study. This is because in an experiment there is a control group and a treatment, which are lacking in this particular survey.

b) What are the explanatory and response variables for this survey?

The response variable in a study is the emphasis of a question whereas the explanatory variable is one that elucidates changes in the response variable. In this particular survey, the explanatory variable is the number of households as this can be manipulated by the researcher whereas the response variable is the opinions on the upcoming elections.

2. A clinical trial was created to study sinus infections. The experimental design is a completely randomized experiment that assigned 250 patients at random among four treatments as given below:

Antibiotic Pill Placebo Pill

Steroid Spray 53 64

Placebo spray 65 68

a) Provide an outline for this experimental design

I. Subjects

The study includes 250 subjects included to study sinus inflections

II. Assignment of subjects

Subjects are assigned randomly using four…