Exam 6: Section 2: Sampling

Although probability sampling is central to criminal justice research, _____. A variety of nonprobability sampling techniques are available in such cases. Nonprobability sampling has its own logic and can provide useful samples for criminal justice inquiry. However, one of the most important goals of all sampling is to reduce, or at least understand, the potential biases that may be at work in selecting subjects.

Probability sampling helps researchers generalize from observed cases to any observed ones.

Simple random sampling forms the basis of probability theory and the statistical tools used to estimate population parameters, standard error, and confidence intervals. Such statistics assume unbiased sampling, and simple random sampling is the foundation of _____.

The standard error is a valuable piece of information because it indicates how closely the sample estimates will be distributed around the population parameter. A larger standard Error indicates _____, while a smaller standard error means that estimates are more clustered around a population parameter.

Sampling is ordinarily used to select observations for one of two related reasons. First, it is often not possible to collect information from all persons or other units we wish to study. For example, we may wish to know what proportion of all persons arrested in U.S. cities have recently used drugs, but collecting all that data would be virtually impossible. Thus, we select a _____.

A population is the theoretically specified grouping of study elements. Whereas the vague term delinquents might describe the target for a study, a more precise description of the population includes the definition of the element delinquents.

Probability theory allows a researcher to draw _____ around the value found in a larger population. With a basic understanding of the logic of probability sampling a researcher can examine how probability sampling works in practice.

A population is the theoretically specified grouping of study elements. For example, a vague term delinquents might describe the target for a study, a more precise description of the population includes the definition of the element delinquents for example, a person charged with a delinquent offense), the _____ for the study charged with a delinquent offense in the previous six months), and often a particular area.

A basic principle of probability sampling is that a sample will be representative of the population from which it is selected if all members of the population have an equal chance of being selected in the sample. Samples that have this quality are often labeled equal probability of selection method EPSEM) samples. Even carefully selected EPSEM samples are _____ of the populations from which they are drawn.

A sampling frame is the list or quasi-list of elements from which a probability sample is selected. It is a sampling frame is a list or quasi-list of target population. It is a "quasi-list" because, even though an actual list might not exist, samples can be drawn as if there were a list. Properly drawn samples provide information appropriate for describing the _____ that compose the sampling frame.

Random selection permits the researcher to link findings from a _____ so as to estimate the accuracy of those findings. All statements of accuracy in sampling must specify both a confidence level and a confidence interval.

An important portion of criminal justice research involves estimating population Parameters on the basis of sample observations. The summary description of a given variable in the sample is called a sample statistic. Sample statistics are used to make _____ parameters.

A sample is _____ from which it is selected if the aggregate characteristics of the sample closely approximate those same aggregate characteristics in the population. For example, if the population, percent contains 50 women, a representative sample will also contain 50 percent or very close to 50 percent women.

A basic principle of probability sampling is that a sample will not be representative of the population from which it is selected if all members of the population have an equal chance of being selected in the sample. Samples that have this quality are often labeled equal probability of selection method (EPSEM) samples.

Snowball Sampling is another type of nonprobability sampling that closely resembles the available-subjects approach. Snowball sampling is commonly used in field observation studies or specialized interviewing. It begins by identifying a single subject or small number of subjects and then asking the subjects to _____.

Sampling in general refers to selecting part of a population. In selecting samples, a researcher wants to do two related things. First, researcher selects samples to represent some larger population of people or other things. Second, the researcher may want to generalize from a sample to an unobserved population the sample is intended to represent.

A sample element is that unit about which information is collected and that provides the basis of analysis. Typically, in survey research, elements are people or certain types of people.

With the inferences and estimations a researcher is able to estimate a population parameter and the expected degree of error on the basis of one sample drawn from a population. The logic of confidence levels and confidence intervals provides the basis for determining the _____ for a study. Once we decide on the sampling error we can tolerate, we can calculate the number of cases needed in our Sample.

Probability sampling techniques enable us to make relatively few observations and then generalize from those observations to a much wider population. For example, if a researcher is interested in what proportion of high school students have used marijuana, collecting data from a _____ of a few thousand students will serve just as well as trying to study every high school student in the country.