Exam 1: The Nature of Statistics

Use the random number table in Appendix A to obtain the required list of random numbers. -A medical researcher is conducting clinical trials. Of the 60 people participating in the trial, 20 will receive a placebo, 20 will receive the experimental drug, and 20 will constitute the control group. The 20 people who will receive the drug will be selected at random. Construct a list of 20 random numbers between 1 and 60 which can be used in obtaining the required simple random sample. Use the random number table and use as your starting point the digits 54 in row 15, columns 20-21.

In a clinical trial, 780 participants suffering from high blood pressure were randomly assigned to one of three groups. Over a one-month period, the first group received a low dosage of an Experimental drug, the second group received a high dosage of the drug, and the third group Received a placebo. The diastolic blood pressure of each participant was measured at the beginning And at the end of the period and the change in blood pressure was recorded. Identify the Experimental units (subjects).

A researcher wishes to assess the working conditions of farm workers at farms in his district. There are 37 farms in the district which are widely scattered geographically. The researcher wishes to interview at least 300 farm workers. Describe a method for selecting a sample which involves cluster sampling. Each farm employs approximately 50 workers.

A magazine publisher mails a survey to every subscriber asking about the timeliness of its subscription service. The publisher finds that only 5% of the subscribers responded. This 5% Represents what?

Which method of sampling is easier: simple random sampling or systematic random sampling?

A political researcher wishes to gauge political sentiment regarding a proposed tax cut. He obtains a list of 1000 email addresses from an internet provider, uses a random number table to select a random sample of 100 of these addresses, emails the people in the sample and requests that they respond to his questions by email. Do you think that the group of people who respond is likely to be representative of all registered voters? Explain your answer.

A statistics student's presentation of the results of her study included many charts, graphs, and tables. Identify the kind of statistical study conducted.

A meteorologist constructs a graph showing the total precipitation in Phoenix, Arizona in each of the months of 1998. Does this involve descriptive statistics or inferential statistics?

In a clinical trial, 780 participants suffering from high blood pressure were randomly assigned to one of three groups. Over a one-month period, the first group received a low dosage of an Experimental drug, the second group received a high dosage of the drug, and the third group Received a placebo. The diastolic blood pressure of each participant was measured at the beginning And at the end of the period and the change in blood pressure was recorded. Identify the factor.

Use the random number table in Appendix A to obtain the required list of random numbers. -A market researcher is conducting a telephone poll. She has a list of 581 registered voters and wishes to interview a random sample of 12 of them. Construct a list of 12 random numbers between 1 and 581 that can be used in obtaining the required simple random sample. Use the random number table and use as your starting point the digits 432 in row 13, columns 10-12.

An education researcher was interested in examining the effect of the teaching method and the effect of the particular teacher on students' scores on a reading test. In a study, there are four Different teachers (Juliana, Felix, Sonia, and Helen)and three different teaching methods (methodA, method B, and method C). The number of students participating in the study is 258. Students are randomly assigned to a teaching method and teacher. Identify the levels of the factor "teaching Method". J

Define probability sampling. Identify some advantages of probability sampling.

Describe the advantages and disadvantages of cluster sampling as compared with simple random sampling.

400 patients suffering from chronic back pain were randomly assigned to one of two groups. Over a four-month period, the first group received acupuncture treatments and the second group received A placebo. Patients who received acupuncture treatments improved more than those who received The placebo.

The table below shows the number of new AIDS cases in the U.S. in each of the years 1989-1994. Year New AIDS cases 1989 33,643 1990 41,761 1991 43,771 1992 45,961 1993 103,463 1994 61,301 Classify the study as either descriptive or inferential.

Identify the study as an observational study or a designed experiment. -A political pollster reports that his candidate has a 10% lead in the polls with 10% undecided.

Provide an appropriate response. -An agricultural researcher wishes to compare the yield of four different varieties of wheat. 64 plots of land are available for an experiment. On each plot of land one of the varieties of wheat will be grown. At the end of the experiment the yield for the different varieties will be compared. 32 of the plots are at one site (site A)and the other 32 are at another site (site B). The soil at site A differs significantly from the soil at site B. If the researcher wishes to design an experiment using completely randomized design, how could the wheat varieties be assigned to the different plots?

Define the terms population and sample.

Give an example of a designed experiment. In your experiment, identify the experimental units, the response variable, the factor(s), the levels of each factor, and the treatments.

In a clinical trial, 780 participants suffering from high blood pressure were randomly assigned to one of three groups. Over a one-month period, the first group received a low dosage of an Experimental drug, the second group received a high dosage of the drug, and the third group Received a placebo. The diastolic blood pressure of each participant was measured at the beginning And at the end of the period and the change in blood pressure was recorded. Identify the levels of The factor.