Which of the following best describes bias

The entire collection of individuals or objects about which information is desired is called a sample. false; populationA study is an observational study if the investigator observes the behavior of a response variable when one or more factors are manipulated. false; experimentalBy definition, a simple random sample of size n is any sample that is selected in a manner to guarantee every individual in the population has an equal chance of selection. true ... but key says falseResponse bias can occur when responses are not actually obtained from all individuals selected for inclusion in the sample. false; non response biasSelection bias can occur if volunteers only are used in a study. trueStratified sampling is a sampling method that in no way involves simple random sampling. falseIncreasing sample size will generally eliminate bias in a sample. falseAs long as the sample size is small relative to the population, there is little practical difference between sampling with replacement and sampling without replacement. trueClusters are non-overlapping subgroups of a population that have been identified as homogeneous. false clusters are heterozygousRandom subpopulations of a population are called strata. False; when an entire population is divided into non overlappingBlocking is a technique that can be used to filter out the effects of extraneous factors. trueA placebo is identical in appearance to the treatment of interest, but contains no active ingredientstrueIn a well-designed experiment, the factors are confounded whenever possible. falseA treatment is any particular combination of values for the explanatory variables. trueTwo factors are extraneous if their effects on the response variable cannot be distinguished from one another. false; extraneous variables are easy to assessRandom assignment to treatments will guarantee groups that are exactly alike for experimental purposes. falseThe method of control wherein an extraneous variable is held constant is called blocking. falseA control group provides a baseline for comparison to a treatment group. trueRandom assignment of volunteers should result in comparable experimental groups. trueIf the subjects as well as the person measuring the response are aware of the treatment assigned to the subject, only single-blinding is being used. false; Replicating in an experiment means that the number of subjects is greater than 1. false; ensures that there is an adequate number of observations for each treatmentWhich of the following statistical studies is an observational study? A) A group of students is surveyed to determine the percentage who believed in reincarnationWhich of the following statistical studies is an experimental study? D) All of these are experimental studies Select the correct sampling method for the following situations.

To analyze the level of employee satisfaction at stores in a certain large city, a grocery store chain selects eight store locations at random and surveys all employees at these locations. C) Cluster Sampling A study is commissioned to determined whether piglets gain body mass more rapidly when a certain hormone is introduced into their feed. In January, a random sample of 40 10-week-old piglets receives a diet that included the hormone. Sixteen weeks later, the average weight increase is determined. A similar experiment is conducted the following June with a random sample of 36 piglets, experiment is conducted the following June with a random sample of 36 piglets, except the hormone is removed from the diet.

Which of the following do you think represent the most serious flaw in the study? A) The presence of a confounding variable. Which of the following best describes the meaning of "variable confounding"? C) Two variables are confounded if their effect on the response variable cannot be distinguished. Which of the following statements is false?

a. The explanatory variables are those variables that have values that are controlled by the experimenter.

b. The response variable is the variable that the experimenter thinks may be affected by the explanatory variables.

c. An experimental unit is the smallest entity to which a treatment is applied.

d. Two variables are confounded if their effects on the response variable can be distinguished.

e. An experiment in which experimental units are randomly assigned to treatments is called a completely randomized experiment. D. Two variables are confounded if their effects on the response variable can be distinginished