BME100 f2014:Group21 L1

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Independent and Dependent Variables

  • Independent variable- Dosage of lipopolysaccharide

LPS is the independent variable because it is not changed by other variables but the effects of changing the amount of this dosage can be seen in the results.

  • Dependent variable - Amount of Inflammotin in the elderly

The amount of Inflammotin in the elderly is the dependent variable because the amount of Inflammotin depends on the amount of LPS given. It depends on the independent variable for its outcome.

Experimental Design

There will be five groups in the experiment.

  • Group 1 will receive a 10mg dose of LPS. This will be a control group.
  • Group 2 will receive a 9mg dose of LPS.
  • Group 3 will receive an 6mg dose of LPS.
  • Group 4 will receive a 3mg dose of LPS.
  • Group 5 will receive a 0mg dose of LPS. This is also a control group.

Group 1 is a control group because 10mg has been proven to raise inflammotin, so the results will be used as a baseline. Group 5 is a control group as well to see if inflammotin is produced by nothing at all. Groups 2, 3, and 4 are experimental groups, as the doses of LPS are manipulated to see if smaller doses will produce LPS. The groups will have different races and gender, as creating separate groups for each ethnicity and gender combination would be too expensive.

The subjects should all be the age of sixty-five, as this test is for the elderly. Maintaining a constant age will help reduce variability in the results.

Number of subjects per group

The number of subjects per group will be 8 and no larger in order to save costs. Since there are 5 groups, there will be 40 individuals needed for the experiment.

Subject Selection

The subject selection will be completely random and single blind. The subjects do not know the dose of the LPS given to them. However, the researchers do know the dose given to the subjects, since the inflammotin results need to be paired up with the corresponding dose of LPS given. Subjects must be age sixty-five.

In order to save money, only residents of Arizona will be selected. A computer will randomly select 40 subjects age 65 for this experiment. If any of the subjects decline, the computer will randomly select replacements. Subjects will be added or dropped from the experiment in order to maintain a 1:1 ratio of men to women, resulting in 20 men and 20 women. The 20 male subjects will be randomly selected again into five groups of four each. The 20 female subjects will also be randomly assigned to five groups of four. Researchers could have bias towards males or females, so the groups will mixed.

Sources of Error and Bias

Sources of error could be from improper measurement of either the LPS given or the inflammotin produced, age, gender, race, or the health of the subjects. This experiment cannot be blinded, because the researchers need to know the dose they are giving their patients. The experiment also does not specify if the researchers are injecting the LPS or if a third party is; the third party could be blinded if this was the case. The researchers may be biased and interpret the LPS as being more or less effective than it really is. Differences in age, race, and gender could affect the levels of inflammotin. The health of the subjects is another source of error, as healthier subjects may produce different amounts of LPS.

A control for the experiment would be to see the levels of inflammotin produced in elderly patients naturally, which is why there is a 0mg dose group. The process to induce it medically can be compared to letting it happen naturally. Another control is the 10mg dose group. It has already been proved that a 10mg dose will increase inflammotin levels, so this group will be used as a baseline. Age can be controlled by maintaining a constant age between the subjects. Gender and race can be controlled by having one group only of Caucasian males, another of African females and so on, but this would not be cost effective. Each experiment would need to be completed twice for each gender, once for each gender. A control for health would be only testing subjects with similar blood pressure, cholesterol, or any other specified criteria.