CJ Trowbridge

USP493 Session 5 Notes

Intro to Statistical Inference

  1. The difference between populations and samples
    1. Statistics and parameters
    2. Using probability sampling to induce population parameters
  2. How to sample
    1. Simple random sample
    2. Stratified samples
    3. Systematic samples
  3. Population, sample and sampling distributions
    1. Sampling distribution defined – the distribution of all possible samples of size n from a population
    2. Population, sample and sampling distribution means
      1. The standard error is the standard deviation of the sampling distribution
    3. Population, sample and sampling distribution standard deviations
  4. The central limit theorem – with a sufficiently large sample size (50 plus) the sampling distribution approaches a normal distribution
  5. Using sampling distributions
    1. The confidence interval
      1. Defined – estimating a population mean or proportion from the sample estimate
      2. The notion of a confidence level – risk of being wrong
      3. How sample size affects the confidence level
    2. Calculations
      1. Select the confidence level – usually 95 or 99
      2. Look up the z score corresponding to your chosen confidence level
      3. Calculate the standard error
      4. Multiple the standard error by the z score corresponding to your chosen confidence level
      5. Add and subtract the result from “iv” to your sample mean to get the confidence interval
  6. Using spss to construct confidence intervals
  7. ARCGIS
    1. The elements of a map
      1. GEODATABASE – a folder with the extension gbd that stores the related elements needed to make maps
      2. It stores the geographic references and the attribute data needed to create a map
      3. FEATURE CLASS – basically a layer. It includes attribute data and the relational locational aspects necessary to map it. (e.g. longitude and latitude
      4. BASEMAP –  collection of background geographic information and related features (e.g. streets) that serves as background to the map.
      5. Types of GIS MAPS
        1. Vector – consists of point line and polygos
        2. Raster – consists of cells (think of pixels) used to show e.g topography

Homework

Chapter 8 spss problem 1, chapter exercise problem 10

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