exam ii: ch9 Flashcards
defines the selected group of people or elements from which data are collected for a study
sample
an entire set of individuals or elements who meet the sampling criteria
target population
portion of the target population to which the researcher has reasonable access
accessible population
individual units of the population and sample
elements
extending the findings from the sample under study to the larger population
- Influenced by quality and consistency of study
generalization
characteristics that the subject/element must possess to be part of the target population
inclusion criteria
characteristics that can cause a person/element to be excluded from the target population
exclusion criteria
as similar as possible to control for extraneous variables
homogenous sample
represents a broad range of values
heterogenous sample
the sample, accessible, and target populations are alike in as many ways as possible
- May be evaluated in terms of the setting, characteristics of the participants, number of participants in a study
representativeness
the difference between the population mean and the mean of the sample
- Want the mean to be as close as possible
- Probability of error increases when the sampling process is not random
sampling error
expected difference in values that occurs when different subjects from the same sample are examined
random variation
consequence of selecting subjects whose measurement values differ in some way from those of the population
systematic variation/systemic bias
% of subjects who declined to participate in the study
refusal rate
how to calculate refusal rate?
If 80 approached, 4 refused
4/80 = 0.05 x 100 = 5% refusal rate (good!)
% of subjects who consented to be in the study
acceptance rate
how to calculate acceptance rate?
80 approached and 76 accepted
76/80 = 0.95 x100 = 95% acceptance rate (good!)
withdrawal or loss of subjects from a study
sample attrition
how to calculate sample attrition?
of subjects withdrawing/number of subjects x 100
number of subjects who remain in and complete a study
sample retention
type of sampling that increases the representativeness of the sample based on the target population
random sampling
what is the difference between control group vs comparison group?
control: used in studies with random sampling
comparison: not randomly determined
a listing of every member of the population, using the sampling criteria to define membership in the population
sampling frame
outlines strategies used to obtain sample for a study
sampling plan
type of sampling in which each person/element in population has an opportunity to be selected for a sample (random sampling)
probability sampling plans
type of sampling in which not every element of a population has the opportunity to be selected for study sample
nonprobability sampling plans
type of probability sampling that is achieved by randomly selecting elements from the sampling frame
simple random sampling
type of probability sampling that is used in situations in which the researcher knows some of the variables in the population that are critical for achieving representativeness.
stratified random sampling
type of probability sampling in which a researcher develops a sampling frame that includes a list of all the states, cities, institutions, or clinicians with which elements of the identified population can be linked
cluster sampling
type of probability sampling when an ordered list of all members of the population is available
systematic sampling
simple random sampling, stratified random, cluster, systematic sampling
types of probability sampling
type of nonprobability sampling; accidental sampling, inexpensive, accessible, usually less time consuming to obtain
convenience sampling
type of nonprobability sampling that shares a similar technique to convenience BUT adds strategy to ensure the inclusion of participant types that are likely to be underrepresented in the convenience
quota sampling
type of nonprobability sampling in which efforts are made to include typical/atypical subjects
- Based on researcher’s judgment
purposeful sampling
type of nonprobability sampling that takes adv of social networks to get the sample
- One person in sample asks another to join, so on
network sampling (snowball sampling)
type of nonprobability sampling that is used in grounded theory research; data are gathered from any individual/group that can provide relevant data for theory generation
- sample is saturated when data collection is complete (per researcher’s judgement)
theoretical sampling
convenience, quota, purposeful, network, theoretical sampling
types of nonprobability sampling
the ability of the study to detect differences or relationships that actually exist in the population
powr
the ability to detect differences in the population or capacity to correctly reject a null hypothesis
- standard power =
- types of level of significance?
power analysis
- standard power = 8
- levels of significance (alpha 0.05, 0.01, 0.001)
what is the most common power analysis/level of significance?
alpha = 0.05
the presence of the phenomenon; extent to which null hypothesis is false
- Increased sample size = increase variability = increased effect size
effect size
concept that asks if the tool used a reliable and valid measure of the variable
measurement sensitivity
anova, t-test, chi-square
types of data analysis techniques
explain the following research settings
- natural
- partially controlled
- highly controlled
- natural: uncontrolled, real life situation/environment
- partially controlled: an environment that is manipulated/modified in some way by the researcher
- highly controlled: environmentally structured for the purpose of conductive research (lab)
what is the difficulty with longitudinal studies?
subject attrition and maturation = can affect outcomes
descriptive, correlational, and outcomes need _____ samples
large samples
quasi and experimental need ____ samples
- and why?
smaller samples bc need higher control
what is the weakest technique for data analysis?
chi square bc needs a large sample size to achieve acceptable levels of power
as the # of categories increases, the sample size must _____
increase
what type of sampling is mostly implemented in grounded theory research?
theoretical sampling
