sampling - Answers selecting a relatively small number of elements from a larger defined group of
elements and expecting the information from the small group will provide accurate judgments about
the larger group
central limit theorem - Answers describes the theoretical characteristics of a sample
- normal distribution occurs sample size is sufficient enough (n is greater than/equal to 30)
- random sample mean (x) approximates population mean (u)
- gets closer to population mean as sample size approaches population
population - Answers an identifiable group of elements of interest to the researcher and pertinent to
the information problem
defined target population - Answers the more specific set of elements identified for investigation
sampling unit - Answers the individual elements within a defined target population
sampling frame - Answers the list of all sampling units accessible for selection during the sampling
process
probability sampling - Answers each sampling unit in the defined target population has a known
probability of being selected for the sample
- can access sampling error
- more generalizable
nonprobability sampling - Answers sampling designs in which the probability of selection of each
sampling unit is not known
- the selection of sampling units is based on the judgment of the researcher and may or may not be
representative of the target population
4 probability sampling methods - Answers simple random, systematic, cluster, stratified
4 nonprobability sampling methods - Answers convenience, judgment, referral, quota
simple random sampling - Answers a procedure in which every sampling unit has a known and equal
chance of being selected
- unbiased estimate of population's characteristics
- valid representation of defined target market
- difficult to obtain a complete and accurate listing of the target population elements
systematic random sampling - Answers similar to simple random sampling but the defined target
population is ordered in some way (eg. customer list, taxpayer roll, or membership roster) and
sampling units selected systematically
- selected according to their position using a skip interval
- easy way to draw sample while ensuring some randomness
- preferable for field sampling
- possibility of hidden patterns
- must know the number of sampling units prior
steps of drawing a systematic random sample - Answers 1. Obtain patient list in alphabetical order
2. Determine sample size needed out of total sampling frame
3. Divide N by n to get the skip interval (k)
4. Use random number-generator to determine start point
5. Select every kth patient in the sample until sample requirements filled.
stratified random sampling - Answers separation of the target population into different sub-groups,
called strata, and the selection of samples from each stratum
- representativeness of sample
- comparisons between strata
- greater estimates of target population with less error
- determining basis of stratifying
proportionately stratified sampling - Answers a stratified sampling method in which each stratum in
the sample is dependent on its size in the population
- larger strata are more heavily sampled
disproportionately stratified sampling - Answers a stratified sampling method in which the size of
each stratum is independent of its size in the population
- using a heuristic instead eg. 10 people from each strata
cluster sampling - Answers a method in which the sampling units are divided into mutually exclusive
and collectively exhaustive
, sub-populations, called clusters
- eg. multiple customer lists for different days of the week
- includes area sampling
- cost effective and easy to implement
- accidentally get homogenous clusters that are distinct to other clusters
area sampling - Answers a form of cluster sampling in which the clusters are formed by geographic
designations
judgment sampling - Answers a sampling method in which participants are selected according to an
experienced individual's belief that they will meet the requirements of the study
convenience sampling - Answers a sampling method in which samples are drawn at the convenience
of the researcher
quota sampling - Answers participants are selected according to pre-specified quotas regarding
demographics, attitudes, behaviors, or some other criteria
snowball sampling - Answers selecting participants by finding one or two participants and then asking
them to refer you
to others
- called referral sampling
3 factors that influence sample size - Answers increase sample size:
- increase population variance and population standard deviation
- increase level of confidence desired in the estimate
- decrease degree of acceptable amount of error in the sample estimate
standard deviation - Answers a measure of variability that describes an average distance of every
score from the mean
- square root of variance
confidence level - Answers the estimated probability that a population parameter lies within a given
confidence interval
acceptable error - Answers acceptable difference between sample result and population value
probability sampling sizes - Answers use sample size formulas to estimate population mean and
population proportions
- if use of formulas leads to sample size larger than 5% of the population, then calculated sample size
should be multiplied by correction factor
population mean - Answers the sum of the values in the population divided by the population size
population proportion - Answers ratio of members of a population with a particular characteristic to
the total members of the population
sample size correction factor - Answers statistical adjustment used when sampling without
replacement from a small, finite population, specifically when the sample size exceeds 5% of the total
population
- it reduces the standard error to improve precision
- square root of (N - n / N -1)
nonprobability sampling sizes - Answers sample size formulas do not apply because determining the
sample size is subjective- use intuitive judgment
- use other determination approaches:
budget, previous sample sizes, standards of the field
construct selection/development - Answers identify and define what is to be measured
- what are subcomponents and dimensions?
construct development - Answers process in which researchers identify characteristics that define the
concept being studied
- determine objective and subjective properties
- identify subcomponents
- construct indirectly measured by taking individual scores from subdimensions and combining them
into single score
construct - Answers a hypothetical variable made up of a set of component responses or behaviors
that are thought to be related
constructs of interest - Answers
components of a construct - Answers
measurement - Answers an integrative process of determining the intensity (or amount) of
information about constructs or variables