Research Methods Ch 5

______ _______ is a portion of the target population consisting of individuals who are accessible to be recruited as participants in the study

accessible population

the major threat to selecting a representative sample is ____

bias

____ ____ is one that has characteristics noticeably different from those of the population.

biased sample

This procedure is called ____ _____ and can be used whenever well-defined clusters exist within the population of interest. NOTES This sampling technique has two clear advantages. First, it is a relatively quick and easy way to obtain a large sample. Second, the measurement of individuals can often be done in groups, which can greatly facilitate the entire research project. Instead of selecting an individual and measuring a single score, the researcher can often test and measure the entire cluster at one time and walk away with 30 scores from a single experimental session. The disadvantage of cluster sampling is that it can raise concerns about the independence of the individual scores.

cluster sampling

The most commonly used sampling method in behavioral science research is probably ____ _____. In ____ _____, researchers simply use as participants those individuals who are easy to get. NOTES Convenience sampling is considered a weak form of sampling because it does not require knowledge of the population and does not use a random process for selection. Despite this major drawback, convenience sampling is probably used more often than any other kind of sampling. It is an easier, less expensive, more timely technique than the probability sampling techniques, which involve identifying every individual in the population and using a laborious random process to select participants. It also is possible for a convenience sample to use techniques borrowed from systematic sampling or cluster sampling.

convenience sampling.

another factor influencing sample size is research _____. If a sample is too large, then it is unnecessarily using extra subjects or participants, which can be views as ______

ethical unethical

Most populations are so ____ that the probabilities remain essentially unchanged from one selection to the next, even when we do not replace individuals.

large

The first principle is the simple observation that a ____ _____ is probably more representative than a small sample. In the field of statistics, this principle is known as the ___ ____ ____ ____ and states that the larger the sample size, the more likely it is that values obtained from the sample are similar to the actual values for the population.

large sample law of large numbers

In _______ ______, the population is not completely known, individual probabilities cannot be known, and the sampling method is based on factors such as commonsense or ease, with an effort to maintain representativeness and avoid bias.

nonprobability sampling

In the terminology of research design, the large group of interest to a researcher is called the ________

population

a sample is selected from a ______ and is intended to represent that ______

population population

In the terminology of research design, the large group of interest to a researcher is called the ______, and the small set of individuals who participate in the study is called the _____.

population ; sample

In _____ ______, the entire population is known, each individual in the population has a specifiable probability of selection, and sampling occurs by a random process based on the probabilities.

probability sampling

____ _____ techniques have a very good chance of producing a representative sample because they tend to rely on a random selection process. simple random sampling by itself does not guarantee a high degree of representativeness.

probability sampling

a sample is obtained such that the proportions in the sample exactly match the proportions in the overall population. This kind of sampling is called _____ _____ ____ ____ or simply ____ ___ ____ NOTES Proportionate random sampling is used commonly for political polls and other major public opinion surveys in which researchers want to ensure that a relatively small sample provides an accurate, representative cross-section of a large and diverse population. The sample can be constructed so that several variables such as age, economic status, and political affiliation are represented in the sample in the same proportions in which they exist in the population.

proportionate stratified random sampling or simply proportionate random sampling.

In the same way that we used stratified sampling to ensure that different subgroups are represented equally, ____ sampling can ensure that subgroups are equally represented in a convenience sample.

quota

A ____ _____ is a procedure that produces one outcome from a set of possible outcomes. The outcome must be unpredictable each time, and the process must guarantee that each of the possible outcomes is equally likely to occur.

random process

to generalize the results of a study to a population, the researcher must select a _______ _________

representative sample

how accurately we can generalize the results from a given sample to the population depends on the __________ of the sample. The degree of representativeness of a _____ refers to how closely the ______ mirrors or resembles the population

representativeness sample; sample

one fundamental question in obtaining a smaple that is representative of the population, is determining how large the ___ should be to be representative

sample

the small set of individuals who participate in the study are called the ______

sample

research studies typically use the results from a relatively small _____ as the basis for answering questions about a relatively large ______

sample population

the goal of the research study is to examine the ______, then generalize the results to the entire ________

sample; population

the process of selecting individuals for a study is called ________

sampling

researcher developed a variety of differnet _______ _______, which fall into two categories: _____ ______ and _____ ______

sampling methods probability sampling and non-probability sampling

___ ____ _____ - This method requires that an individual selected for the sample be recorded as a sample member and then returned to the population (replaced) before the next selection is made. This procedure ensures that the probability of selection remains constant throughout a series of selections. this is an assumption of many of the mathematical models that form the foundation of statistical analysis

sampling with replacement

____ ____ ____ - As the term indicates, this method removes each selected individual from the population before the next selection is made. This method guarantees that no individual appears more than once in a single sample. However, each time an individual is removed, the probability of selection changes for the remaining individuals.

sampling without replacement

_____ ______ means that the sampling procedure favors the selection of some individuals over others.

selection bias

The logic behind ____ ____ ____ is that it removes bias from the selection procedure and should result in representative samples.

simple random sampling

The starting point for most probability sampling techniques is ____ ____ ____. The basic requirement for random sampling is that each individual in the population has an equal chance of being selected. Equality means that no individual is more likely to be chosen than another. A second requirement that is sometimes added is that each selection is independent of the others. Independence means that the choice of one individual does not influence or bias the probability of choosing another individual.

simple random sampling

Often, a researcher's goal for a representative sample is to ensure that each of the different subgroups is adequately represented. One technique for accomplishing this goal is to use ______ _____ ______. NOTES ____ _____ _____ is particularly useful when a researcher wants to describe each individual segment of the population or wants to compare segments. The main advantage of a stratified random sample is that it guarantees that each of the different subgroups will be well represented with a relatively large group of individuals in the sample. Thus, this type of sampling is appropriate when the purpose of a research study is to examine specific subgroups and make comparisons between them. When using stratified sampling the two subgroups would be represented equally in the sample (with 25 children from each group) but the subgroups are not equally represented in the population. ____ ____ _____ does not produce a true random sample because all individuals in the population are not equally likely to be selected.

stratified random sampling

____ _____ is a type of probability sampling that is very similar to simple random sampling. Systematic sampling begins by listing all the individuals in the population, then randomly picking a starting point on the list. This technique is less random than simple random sampling because the principle of independence is violated.

systematic sampling

____ _____ is the group defined by the researcher's specific interests. Individuals in a target population typically share on _______

target population characteristics