Question

For each of the studies in #1 through #4, answer the following questions a)What is the response variable? b)What is the study unit? c)What are the factor(s)? For each factor, give the corresponding factor levels. d)Ifit is a multi-factor study, list the treatments. e) Is the study experimental, observational or mixed? Why? Explain in terms of the factors In a study to determine if proficiency test scores are affected by the education of a child's parents, a random sample of 9-year old children was drawn. Each child's test score and the educational level of the parent with the higher level were recorded. The education categories were: < high school, high school graduate, some university, university graduate 2. A manufacturer of outdoor brass lamps has received numerous complaints about premature corrosion. The manufacturer has identified the cause of the problem as the low-quality lacquer used to coat the brass. It is decided to replace the current lacquer with one of 5 possible alternatives. To determine which one is best a study is carried out in which 25 randomly chosen lamps are coated with lacquer #1, another 25 lamps are randomly chosen to be coated with lacquer #2, etc. All 125 lamps are put outside and for each, the number of days until the first sign of corrosion is recorded.

Answer 1

1.
a) The response variable is proficiency test score.

b)
The study unit are 9 year old children.

c)
The factor is education of a child's parents. The factor levels are < high school, high school graduate, some university, university graduate

d)
As, there is only one factor (education of a child's parents), it is not a multi-factor study.

e)
We are observing education of a child's parents and proficiency test score and their relation and we do not have control over the factor - education of a child's parents . We are not giving any treatments to random sample of study units (students).
So, this is an observational study.

2.
a) The response variable is number of days the first sign of corrosion occurs.

b)
The study unit are outdoor brass lamps.

c)
The factor is lacquer. The factor levels are lacquer #1, lacquer #2, lacquer #3, lacquer #4, lacquer 5.

d)
As, there is only one factor (lacquer), it is not a multi-factor study.

e)
We have control over the factor - lacquer . We are giving treatments (coating with 5 varieties of lacquer) to random sample of 25 study units (lacquer) and observing the response variable (number of days the first sign of corrosion occurs).
So, this is an experiment.