Exam 1: The Nature of Statistics

A designed experiment is described. Identify the specified element of the experiment. -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 response Variable.

A news article appearing in a national paper stated that "The fatality rate from use of firearms sank to a record low last year, the government estimated Friday. But the overall number of violent Fatalities increased slightly, leading the government to urge an increase in police forces in major Urban areas. Overall, 15,600 people died from violent crimes in 2005, up from 15,562 in 2004, According to projections from a government source. Is the figure15,600 a descriptive statistic or an Inferential statistic? Is the figure 15,562 a descriptive statistic or an inferential statistic? The figure15,600 is a descriptive statistic since it reflects the actual number of deaths from violent crimes for the year 2004.

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 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 randomized block design, how could the wheat varieties be assigned to the different plots?

In a poll of 50,000 randomly selected college students, 74% answered "yes" when asked "Do you have a television in your dorm room?" Identify the sample and population.

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. The researcher wishes to design an experiment. In this example, why might a randomized block design, with blocking by soil type, be preferable to a completely randomized design?

Provide an appropriate response. -Describe the steps involved when using stratified random sampling with proportional allocation. What are the advantages of this sampling method?

Why do statisticians sometimes use inferential statistics to draw conclusions about a population? In what situations might a statistician draw conclusions about a population using descriptive statistics only?

Identify the study as an observational study or a designed experiment. -A clinic gives a drug to a group of ten patients and a placebo to another group of ten patients to find out if the drug has an effect on the patients' illness.

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 factors.

In simple random sampling, each possible sample is equally likely to be the one obtained.

The human resources department of a large, well-known telecommunications firm is behind schedule in sampling the job satisfaction of the company's employees. In an effort to catch-up, the HR manager quickly goes down an alphabetical list of employees and e-mails a survey to every Tenth employee. An neutral third party collects all surveys and ensures all of the selected Employees respond to the survey. What sampling method best describes what the HR manager is Doing?

The finalists in an essay competition are Lisa (L), Melina (M), Ben (B), Danny (D), Eric (E), and Joan (J). Consider these finalists to be a population of interest. List the 20 possible samples (without Replacement)of size three from this population of six finalists.

Describe a double-blind experiment and explain why blinding is used. Define the term "placebo effect" as part of the answer.

George, a network engineer, ordered 700 CAT 5e Ethernet cables for use at his company's network. After receiving these cables, he decided to randomly test 210 of these cables before using them. He Was alarmed to find out that 91% of these cables failed completely. He returned the entire lot to the Manufacturer. When he tested the cables, what was George's sample?

A designed experiment is described. Identify the specified element of the experiment. -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 experimental 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 treatments.

Use the random number table in Appendix A to obtain the required list of random numbers. -A company employs 5382 people and wishes to interview a random sample of 14 of them with regard to the company's health insurance policy. Construct a list of 14 random numbers between 1 and 5382 that can be used in obtaining the required simple random sample. Use the random number table and use as your starting point the digits 0691 in row 3, columns 30-33.

The finalists in an essay competition are Lisa (L), Melina (M), Ben (B), Danny (D), Eric (E), and Joan (J). Consider these finalists to be a population of interest. The possible samples (without Replacement)of size two that can be obtained from this population of six finalists are as follows. L,M L,B L,D L,E L,J M,B M,D M,E M,J B,D B,E B,J D,E D,J E,J If a simple random sampling method is used to obtain a sample of two of the finalists, what are the chances of selecting Lisa and Danny?

Thirty of the 198 students enrolled in Statistics 101 were asked if they wanted Exam II to be a take-home or an in-class assessment. Twenty, or about 67%, of the students polled indicated a Preference for an in-class exam. The professor concluded that the majority of students in Statistics 101 would prefer an in-class examination for the second assessment. Did the professor perform a Descriptive study or an inferential study?

A computer network manager wants to test the reliability of some new and expensive fiber-optic Ethernet cables that computer department just received. The computer department received 7 Boxes containing 50 cables each. The manager does not have the time to test every cable in each Box. The manager will choose one box at random and test 10 cables chosen randomly within that Box. What is the sample?

In a designed experiment, explain the difference between the treatments and the factors.