Statics

Statics

1. Visual Displays of data

   • Displays
     • histogram
     • stem and leaf
     • bar graphs
     • circle graphs
     • line graphs
   • frequency distribuition
     • frequency
       • how many times it happens
     • relative frequency
       • how many times happens comparing to the population

2. Basic concepts

   • Static
     • a measure of overview that is calculated to describe a characteristic of a single sample of the population.
   • Parameter
     • measure of overview that is calculated to describe a characteristic of a population.
   • Population
     • is the totality of the elements or things under consideration
   • Random Variables
     • Qualitative
       • variables produce categorical responses
     • Quantitavie
       • produce numerical answers; quantify an element of the population.
   • Sample
     • the portion of the population that is selected for analysis.

3. Measures scales

   • Properties of Measurement Scales
     • identity
       • Each value on the measurement scale has a unique meaning.
     • magnitude
       • Values on the measurement scale have an ordered relationship to one another. That is, some values are larger and some are smaller.
     • equal intervals
       • Scale units along the scale are equal to one another. This means, for example, that the difference between 1 and 2 would be equal to the difference between 19 and 20.
     • a minimum value of zero
       • . The scale has a true zero point, below which no values exist.
   • nominal scale
     • variables represent a descriptive category, but have no inherent numerical value with respect to magnitude.
   • ordinal scale
     • ordered relationship to every other value on the scale.
   • Interval Scale of Measurement
     • properties of identity, magnitude, and equal intervals.
   • Ratio Scale of Measurement
     • satisfies all four of the properties of measurement: identity, magnitude, equal intervals, and a minimum value of zero.

4. Sampling Methods

   • • Population parameter.
     • true value of a population attribute.
   • • Sample statistic
     • an estimate, based on sample data, of a population parameter.
   • • Probability samples
     • With probability sampling methods, each population element has a known (non-zero) chance of being chosen for the sample.
   • • Non-probability samples.
     • we do not know the probability that each population element will be chosen, and/or we cannot be sure that each population element has a non-zero chance of being chosen.
     • • Voluntary sample
       • made up of people who self-select into the survey.
     • • Convenience sample.
       • A convenience sample is made up of people who are easy to reach.
   • Probability Sampling Methods
     • • Simple random sampling
       • any sampling method that has the following properties.
         • o The population consists of N objects. o The sample consists of n objects. o If all possible samples of n objects are equally likely to occur, the sampling method is called simple random sampling.
     • Probability Sampling Methods
       • • Stratified sampling
         • With stratified sampling, the population is divided into groups, based on some characteristic.
       • • Cluster sampling
         • With cluster sampling, every member of the population is assigned to one, and only one, group
       • • Multistage sampling.
         • we select a sample by using combinations of different sampling methods.
       • sampling. With systematic random sampling, we create a list of every member of the population.
         • • Systematic random

5. Measures of dispersion

   • Coefficent of variation
     • s/x
   • Chevyshevs teorem
     • 1/1/k2
   • standard deviation
     • sum of (x-x)2/n

6. measures of position

   • decile
     • 10 to 10
   • percentile
     • %
   • quartitle
     • 25 to 25
   • z-score