Flashcards
STATS SAMPLING
Flashcards do conjunto (22)
- 1Purpose of SamplingTo obtain a set of individuals from a population that would capture the complexity of that population
- 2Advantages of Sampling1. Necessary in large populations
2. Efficient/cost effective method of data collection
3. More highly detailed information - 3Disadvantages of SamplingMay be Sampling Error
- 4Sources of Sampling Error1. Problems with sampling procedures
2. Operational logistic, or personal problems
3. Improper sampling designs - 5Sampling Procedure Steps1. Define target population
2. Designate sampled population and sampled area from sampling frame
3. Select sampling design
4. Design research instrument and operational plan
5. Conduct Pretest
6. Collect sample Data - 6Target Population/AreaA particular group of individuals that the data is to be collected on.
- 7Sampling population/areaProcess of taking a subset of subjects from the entire population.
- 8sampling frameA list of items or people from a population from which a sample is taken
- 9oversamplingOne area or group receives too many samples in comparison to others.
- 10undersamplingWhen one area or group receives too little samples in comparison to others
- 11Non-Probability Sampling DesignsJudgmental or Purposeful
Convenience or Accessibility
Quota
Volunteer - 12Probability Sampling DesignsSimple Random Sample
Systematic and Grid Sample
Stratified Sample
Cluster Sample
Hybrid or Combination Sample - 13Simple Random Sample Pros and ConsEach possible sample has an equal probability of being selected
Pros: Simple to use and easy to estimate minimum sample size
Cons: Sample points are not uniformly dispersed throughout the area - 14Systematic and Grid Sampling Pros and ConsCollection of samples at specific intervals
Pros: Obtain large sample quickly, offers representative and proportional coverage of entire sample area
Cons: Sampling frame needs to be random without ordering - 15Point estimationDescriptive stats for sample
Central Tendency measures - 16Interval estimationExamines range of values
Level of precision - 17Parameter vs StatisticParameters are values that characterize the population
Statistic is the known value calculated from a sample used to estimate the parameter. - 18Central Limit TheoremAs the sample number approaches the true population number, the sample gets closer to normal distribution.
When N is large, the sample approaches normal distribution curve. - 19Standard Error of the MeanMeasure of standard deviation for a sample
Indicates how much a sample mean differs from the population mean - 20Law of Large NumberThe larger the sample size, the more likely the sample will represent the true population.
- 21Confidence level vs. Significance LevelConfidence Interval is the probability that the interval surrounding the sample mean includes the true population mean.
Significance level is the sample error. - 22Stratified Sample Pros and ConsPopulation or target area is separated into subgroups and then select a simple random sample from each
Pros: Could reduce costs associated with sample selection
Cons: A deep understanding to make strata is essential
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- FlashCards sobre STATS SAMPLING, criado por James Foster9258 em 29-03-2015.
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- James Foster9258
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