Chapter 14 Flashcards
Sampling
Sampling
the process of selecting a sufficient number of elements from the population— the sample is generalizable to the population
population
refers to the entire group of people, events or things of interest that the researcher wishes to investigate
unit of observation
level at which your data are measured or collected
element
a single member of the population
unit of analysis
level at which information is analyzed and conclusions are drawn
subject
a single member of the sample— like an element is a single member of a POPULATION
a representative sample is…
a sample that reflects the population accurately
a miniature of the population from which it is drawn
central limit theorem
the sampling distribution of the sample mean is normally distributed
what are the 5 steps of the sampling process?
- define the population
- determining the sample frame
- determining the sampling design
- determine the sample size
- execute the sampling process
probability sampling
- elements in the population have a known and non-zero chance of being chosen as subjects in sample
- used when the researcher wants to generalize the research findings to the population
what is SRS and an advantage and disadvantage of it
all elements in the population are considered and each element has an equal chance of being chosen as the subject
- high generalizability of findings
- not as efficient as strat. sampling
what is systematic sampling and an advantage and disadvantage of it
every nth element in the population is chosen starting from a random point in the sampling frame
- easy to use if sampling frame is available
- systematic biases are possible
what is stratified random sampling
segregation followed by selection of subjects from each stratum
proportionate stratified random sampling:
once stratified; a sample of members from each stratum can be drawn that is proportionate to the total # of elements in their respective strata
disproportionate stratified random sampling
the # of subjects from each stratum would be altered, but the overall sample size remain the same
what is cluster sampling and a advantage and disadvantage of it
groups that have heterogenous members are first identified; then some are chosen at random and the random chosen ones are studied
- good in geographic clusters, costs of data collection are lo
- least reliable and efficient
what is non-probability sampling
elements in the population do not have any probabilities attached to their being chosen as sample subjects
what is convenience sampling
most easily accessible members are chosen as subjects
what is judgement sampling
subjects selected on the basis of their expertise in the topic of the research
what is quota sampling
ensures that certain groups are adequately represented in the study
what are the 3 way that help you decide what sample type to use
- extent of prior knowledge in the area of research undertaken
- the main objective of the study
- cost considerations
precision
refers to how close our estimate is to the true population characteristic
confidence
how certain we are that our estimates will really hold true for the population
what are sampling issues in online research
- difficulty establishing a sample frame
- links are posted on social media
- leads to non-probability samples
- self-selection bias
- response rates are usually low
