# Intro to Statistical Inference

- The difference between populations and samples
- Statistics and parameters
- Using probability sampling to induce population parameters

- How to sample
- Simple random sample
- Stratified samples
- Systematic samples

- Population, sample and sampling distributions
- Sampling distribution defined – the distribution of all possible samples of size n from a population
- Population, sample and sampling distribution means
- The standard error is the standard deviation of the sampling distribution

- Population, sample and sampling distribution standard deviations

- The central limit theorem – with a sufficiently large sample size (50 plus) the sampling distribution approaches a normal distribution
- Using sampling distributions
- The confidence interval
- Defined – estimating a population mean or proportion from the sample estimate
- The notion of a confidence level – risk of being wrong
- How sample size affects the confidence level

- Calculations
- Select the confidence level – usually 95 or 99
- Look up the z score corresponding to your chosen confidence level
- Calculate the standard error
- Multiple the standard error by the z score corresponding to your chosen confidence level
- Add and subtract the result from “iv” to your sample mean to get the confidence interval

- The confidence interval
- Using spss to construct confidence intervals
- ARCGIS
- The elements of a map
- GEODATABASE – a folder with the extension gbd that stores the related elements needed to make maps
- It stores the geographic references and the attribute data needed to create a map
- FEATURE CLASS – basically a layer. It includes attribute data and the relational locational aspects necessary to map it. (e.g. longitude and latitude
- BASEMAP – collection of background geographic information and related features (e.g. streets) that serves as background to the map.
- Types of GIS MAPS
- Vector – consists of point line and polygos
- Raster – consists of cells (think of pixels) used to show e.g topography

- The elements of a map

## Homework

Chapter 8 spss problem 1, chapter exercise problem 10