Exam 2: An Introduction to Statistics and Statistical Inference

Mice are given a protein injection that is designed to promote physical growth.Fifty mice are randomly selected for evaluation in the study.Some of the mice are injected with high levels of the protein, some are injected with low levels of the protein, and a third group receives a placebo (saline injection).The mice's growth is recorded and compared.In this study, the variable is best described as:

Electrical engineers are attempting to maximize the efficiency of an experimental battery cell.They wish to determine the optimum charge rate that will provide the maximum battery capacity.They sample 50 cells and randomly assign five different charge rates to the sample (10 cells for each charge rate).All cells are then discharged at the same rate, with the total battery capacity for each cell being recorded in amp-hours.This is an example of a(n) ______________ study.

Suppose we know that a population consists of equally likely numbers 1 to 6, inclusive (in other words, we know everything about the population).We wish to answer questions concerning a sample of two distinct numbers from this population.This is best described as a _____________ problem.

Lenders base applicants' eligibility for home loans on the perspective borrower's credit score.Recent failures of lending corporations have prompted a study of the adherence of lenders to lending guidelines.Two thousand home loans extended between the years 1995 and 2005 are randomly selected for audit.The borrower's credit score is recorded and compared with the normal benchmark for the loan.The population in this study is:

The 2009 National Survey on Drug Use and Health selected a random sample of U.S.college students and asked them about possible illicit drug use.Approximately 23% of the students surveyed reported using illicit drugs in the past year.The sample in this study is:

The 2009 National Survey on Drug Use and Health selected a random sample of U.S.college students and asked them about illicit drug use.Approximately 23% of the students surveyed reported using illicit drugs in the past year.The population in this study is:

A psychologist wishes to test a behavioral modification therapy that is claimed to improve the behavior of preteen autistic children.She randomly selects 20 preteen autistic children and exposes half of the group to the behavioral modification therapy; the other half continue with their standard treatment regimen.A standardized behavioral test is administered to each child both before and after treatment.The population in this experiment is:

A clinical nurse supervisor (CNS) is designing an experiment that will evaluate the effectiveness of household pets in treating depression.Using computer software, she generates a list of 200 people.In the sampling process, every possible sample in the population of size 200 has the same chance of being selected.Is this a simple random sample?

A ______________ of size n is a sample selected in such a way that every possible sample of size n has the same chance of being selected.

Inferential statistics is best defined as:

A group of 20 monitor lizards is observed over the course of the lizards' life spans.The total food consumption of each lizard is recorded and displayed on a bar graph.This presentation of raw information in a more user-friendly format is an example of:

The time required to cure concrete is pivotal in the construction business.Insufficient curing time results in lower structural strength, which can create hazardous conditions.Conversely, too much curing time wastes valuable resources and may result in greatly inflated building costs.To help ascertain the minimum curing time, a random sample of 80 poured concrete foundations is drawn.The total time to completely cure each foundation is recorded.This study is best described as a(n) _________________ study.

A quality control engineer oversees the production of rubber seals for aircraft manufacturing.In a standard production run, 25 seals are randomly selected for destructive testing.The seals are physically stressed to their common design limit while exposed to increasing temperature, with the trial ending when the seal fails.Of interest is the temperature at which the seal fails.The variable in this experiment is:

An office manager wishes to survey 5 of the 20 employees for whom she is responsible.She assigns each of the 20 employees a number and writes the number on 20 identical but separate pieces of paper.She places the 20 pieces of paper in a hat, mixes them up, and then blindly draws five numbers to determine which five employees are included in the sample.If the slips of paper are identical and the selection of each employee is equally likely, is this a simple random sample of size 5?

In a(n) _______________, we merely observe the response for a specific variable for each individual or object.

To evaluate the objectivity of a certain professor's grading, 20 classes that she previously taught are randomly selected for auditing.The proportion of male students who pass in each class is compared to the proportion of female students who pass in the same selected class.The sample in this study is:

In a study that seeks to evaluate the effect that caffeine has on individuals with narcolepsy, 40 patients with this condition are randomly selected to participate.Fifteen of the patients are given high doses of caffeine, 15 are given moderate doses, and 10 are given low doses over a period of 30 days.The total amount of time each patient slept over the 30 days was recorded.This is best described as a(n) _________________ study.

In a statistical inference procedure, the claim is best described as:

A behavioral scientist wishes to know more about the walking habits of university students while they are traversing a particular campus sidewalk.She positions herself out of sight of the students who are walking and records the time required for several of them to pass between two fixed points along the sidewalk.This is best described as a(n) ______________ study.

In a study of crop rotation techniques, agricultural researchers are interested in making general statements concerning the effectiveness of a given technique for all corn fields in the state of Kansas.Using a cluster technique, they randomly choose 30 farms from across the state for their study.Some of the chosen farms are randomly selected to use the rotation technique, whereas others are not.In this study, the population is best described as: