# Shared Flashcard Set

## Details

CJ 302 Research Methods
Ch. 8 Probability Sampling
15
Criminal Justice
06/17/2014

Term
 Key Terms: define   Homogenous
Definition
 all members of a population are/were identical in characteristics
Term
 Key Terms: define   Heterogeneous
Definition
 individual members of a population are different from each other in characteristics
Term
 Key Terms: define   Sampling
Definition
 the process of selecting observations (a sample) to provide an adequate description and robust inferences of the population. the sample is a representative of the population
Term
 Key Terms: define   Sample element
Definition
 A case or a single unit that is selected from a population and measured in some way - the basis of analysis
Term
 Key Terms: define   Universe with SIUE example
Definition
 The theoretical aggragation of all possible elements - unspecified to time and space.  ex. SIUE
Term
 Key Terms: define   Population with SIUE example
Definition
 The theoretical aggregation of specified elements as defined for a given survey defined by time and space. ex. SIUE students 2014
Term
 Key Terms: define   Sample or target population with SIUE example
Definition
 The aggregation of the population from which the sample is actually drawn. ex. SIUE summer students 2014
Term
 Key Terms: define   Sample frame with SIUE example
Definition
 A specific list that closely approximates all elements in the population - from this the researcher selects units to create the study sample. ex. List of SIUE summer students 2014
Term
 Key Terms: define   Sample
Definition
 A set of cases that is drawn from a larger pool and used to make generalizations about the population
Term
 Key Concepts   What does sample size depend on?
Definition
 How much sampling error can be tolorrated Size of population varation within the population with respect to the characteristics of interest Smallest subgroup within the sample for which estimates were needed Sample needs to be big enough to properly estimate the smallest subgroup
Term
 Key Concepts   What are the 4 different types of probability sampling?
Definition
 Simple Random Sampling (SRS) Systematic random sampling (SS) Stratified sampling (StS) Cluster sampling
Term
 Key Concepts    Explain Simple Random Sampling (SRS) with method and give example of how this is done
Definition
 The basic sampling method which most others are based on.  Method: a sample size 'n' is drawn from a population 'N' in such a way that every possible element in the population has the same chance of being selected ex. Random number table or drawing out of a hat
Term
 Key Concepts   1.Explain Systematic Random Sampling (SS) method. 2.What does the sampling interval do?  3. why is SS better than SRS?
Definition
 Starting from a random point on a sampling frame, every 'n'th element in the frame is selected at equal intervals. the sampling interval tells the researcher how to select elements from the frame (ex. 1 in 10, 3 in 60), this depends on sample size needed Emperically SS provides the same results but it is more efficent
Term
 Key Concepts   Explain Stratified Sampling (StS) method.
Definition
 Divide the population by certain characteristics into homogeneous subgroups known as strata(s). A systematic sample is taken from each strata relative to the proportion of that stratum to each of the others.
Term
 Key Concepts   Cluster sampling   1. when would this type of sampling be used? 2. what do you trade for efficency?
Definition
 when researchers lack a good sample frame for a dispersed/spread out population.  accuracy
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