Introduction to Statistics

• Statistics: Data
  • Collect
  • Organize
  • Analyze
  • Interpret
• Population: An entire group of individuals that we want information about
• Sample: A part of the population
• Stastical Inference: An estimate or prediction about population based on information obtained in a sample

We can split statistics into two parts:

• Descriptive Statistics
  • Numerical or graphical methods to get the pattern of the dataset
• Inferential Statistics
  • Use the fact about a sample to estimate the population

Data

• Qualitative Data
  • Categorical, cannot be measured
• Quantitative Data
  • Numerical scale
• Frequency - Number of observations (i.e. 2 entries of a subinterval)
• Relative Frequency - Percentage of observations (i.e. 2 entries of a subinterval / 40 total entries)

Graphs

• Histogram
  • Plots frequencies of different intervals

Sometimes we are interested in the shape of the graphed frequencies. Whether it is skewed to the left/right, symmetric, or whatever.