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Monday, August 04, 2008
 Faraz_1984 Banned Join Date: Apr 2008 Location: Alone Posts: 598 Thanks: 787 Thanked 290 Times in 205 Posts
Notes and Topics on Statistics

Definitions
• Statistics
• Collection of methods for planning experiments, obtaining data, and then organizing, summarizing, presenting, analyzing, interpreting, and drawing conclusions.
• Variable
• Characteristic or attribute that can assume different values
• Random Variable
• A variable whose values are determined by chance.
• Population
• All subjects possessing a common characteristic that is being studied.
• Sample
• A subgroup or subset of the population.
• Parameter
• Ch
• aracteristic or measure obtained from a population.
• Statistic (not to be confused with Statistics)
• Characteristic or measure obtained from a sample.
• Descriptive Statistics
• Collection, organization, summarization, and presentation of data.
• Inferential Statistics
• Generalizing from samples to populations using probabilities. Performing hypothesis testing, determining relationships between variables, and making predictions.
• Qualitative Variables
• Variables which assume non-numerical values.
• Quantitative Variables
• Variables which assume numerical values.
• Discrete Variables
• Variables which assume a finite or countable number of possible values. Usually obtained by counting.
• Continuous Variables
• Variables which assume an infinite number of possible values. Usually
• obtained by measurement.
• Nominal Level
• Level of measurement which classifies data into mutually exclusive, all inclusive categories in which no order or ranking can be imposed on the data.
• Ordinal Level
• Level of measurement which classifies data into categories that can be ranked. Differences between the ranks do not exist.
• Interval Level
• Level of measurement which classifies data that can be ranked and differences are meaningful. However, there is no meaningful zero, so ratios are meaningless.
• Ratio Level
• Level of measurement which classifies data that can be ranked, differences are meaningful, and there is a true zero. True ratios exist between the different units of measure.
• Random Sampling
• Sampling in which the data is collected using chance methods or random numbers.
• Systematic Sampling
• Sampling in which data is obtained by selecting every kth object.
• Convenience Sampling
• Sampling in which data is which is readily available is used.
• Stratified Sampling
• Sampling in which the population is divided into groups (called strata) according to some characteristic. Each of these strata is then sampled using one of the other sampling techniques.
• Cluster Sampling
• Sampling in which the population is divided into groups (usually geographically). Some of these groups are randomly selected, and then all of the elements in those groups are selected.
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