[كومة مشآعر]

6- Identify each study as being either observational or experimental.

a. Subjects were randomly assigned to two groups and one group was given an herb and the other group a placebo. After 6 months, the numbers of respiratory
tract infections each group had were compared.

experimental

b. A researcher stood at a busy intersection to see if the color of the automobile that a person drives is related to running red lights.

observational


c. A researcher finds that people who are more hostile have higher total cholesterol levels than those who are less hostile.

observational

d. Subjects are randomly assigned to four groups. Each group is placed on one of four special diets—a low-fat diet, a high-fish diet, a combination of low-fat diet and high-fish diet, and a regular diet. After 6 months, the blood pressures of the groups are compared to see if diet has any effect on blood pressure

experimental

7- Determine whether each statement is true or false. If the statement is false, explain why.



a. Probability is used as a basis for inferential statistics.

True

b. The height of President Lincoln is an example of a variable

false

c. The highest level of measurement is the interval level.

false

nominal level


d. When the population of college professors is divided into groups according to their rank (instructor, assistant professor, etc.) and then several are selected from each group to make up a sample, the sample is called a cluster sample

false

called stratified

e. The variable age is an example of a qualitative variable.

false

Quantitative variables



f. The weight of pumpkins is considered to be a continuous variable

True

8. The number of absences per year that a worker has is an example of what type of data?
a. Nominal
b. Qualitative
c. Discrete
d. Continuous


9. A researcher divided subjects into two groups according to gender and then selected members from each group for her sample. What sampling method was the researcher using?
a. Cluster
b. Random
c. Systematic
d. Stratified


12. A variable that interferes with other variables in the study is called
a. A confounding variable.
b. An explanatory variable.
c. An outcome variable.
d. An interfering variable

Use the best answer to complete these statements.


17. Two major branches of statistics are Deive
and inferential.


18. The group of all subjects under study is called a sample(n)

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