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Statistics

Statistics. A scientific discipline consisting of procedures for collecting, describing and interpreting numerical data. Statistics. Statistical Procedures can be used to: 1. Summarize/describe a body of data - these procedures make up what is termed Descriptive Statistics .

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Statistics

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  1. Statistics A scientific discipline consisting of procedures for collecting, describing and interpreting numerical data

  2. Statistics Statistical Procedures can be used to: 1. Summarize/describe a body of data - these procedures make up what is termed Descriptive Statistics. 2. Take information from a sample to make conclusions about a population - these procedures are called Inferential Statistics.

  3. Population • A population consists of all possible observations which share an individual characteristic or set of characteristics • Identify the populations of the following studies: • Study of incomes of graduate students in the math department at CSULA. • Study of drug use among teenage boys in the US.

  4. Sample • A sample is a subset of the population. • Using Inferential Statistics, information taken from the sample is used to estimate the characteristics of the population.

  5. Sampling • Why sample? Why not use all the data from the population? • Normally, time and resource constraints prohibit acquiring all the data within the defined population.

  6. Sampling • A sample is expected to represent the population • The way the sample is selected is a determinant of how well it represents the population • Handout of number of residents and housing units in cities in LA county

  7. Data • Is the data set a sample or a population? • Give an example of a study using the data in which the data would be considered: • A sample • A population

  8. Biasedness • If the population of our study is all cities in California, the sampling procedure appears to be biased • A biased sampling procedure is one in which some observations in the population are favored over others in selecting the sample

  9. Biasedness • If data is purposely selected only from LA County what is the chance of any city outside of the county getting within the sample? • An unbiased sampling procedure would be one in which every observation within the population has an equal chance of being selected for the sample • If the population consists of all California cities, give an example of an unbiased sampling procedure

  10. Statistics • The first half of econ 209 covers Descriptive Statistics • The second half is an introduction to Inferential Statistics

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