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Comparing an Effected Group to a Control Group

Question: A group of 200 adults aged 21 to 50 were selected from those entering Fit Right Health stores in Washington State, and were randomly divided into two groups. One group was given a herb and the other a placebo. After 6 months, the number of respiratory tract infections in each group were compared.

I. What is the population?
II. What is the sample?
III. Is the study observational or experimental? Justify your answer.
IV. If observational, identify ALL variables. If experimental, identify ALL independent and dependent variables.
V. For each of the variables identified in part IV, list which of the four levels/scales of measurement was used to obtain data on these variables?
VI. Classify each of the variables identified in part IV as either attribute or numerical.

- Classify the following variable as nominal, ordinal, discrete, or continuous and state why it is such a variable: number of bank deposits in a month
- Classify the following as an example of a nominal, ordinal, interval, or ratio level of measurement, and state why it represents this level: gender of employees at a local warehouse
- Construct a frequency distribution table to organize the following set of data:
109 114 111 109 109 106 110 114 114 112
111 110 114 114 110 113 114 105 107 107
- Construct a grouped frequency distribution for the following 28 scores using a class width of 4:
40 39 41 48 27 37 26 33 38 31 38 27 38 46
39 28 36 34 26 37 34 43 42 25 47 29 25 28.

Solution Preview

I. Those entering Fit Right Health stores in Washington State

II. A group of 200 adults

III. The study is observational since different manipulation (herb versus placebo) is executed.

IV. Independent variable: the group given a herb and the other a placebo
Dependent variable: the number of respiratory tract infections.

V. Independent variable is a nominal variable;
Dependent variable is interval variable.

VI. Independent variable is attribute and dependent variable is numerical.

- Classify the following variable as nominal, ordinal, discrete, ...

Solution Summary

The solution compares an effected group to a control group.

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