Statistics

1
Statistics

• Statistics is a collection of methods for
• Planning experiments and surveys
• Obtaining data
• Organizing, summarizing, presenting, analyzing,
  interpreting, and drawing conclusions based on
  data (observations that have been collected)

2
Population/Sample

• Population the group to be studied
• Sample a subgroup of the population
• In a census, we collect data from the entire
  population
  
• In a sample, we collect data from the sample
  (usually to try to draw conclusions about the
  population)

3
Whats the population sample?

• A congressperson reads 350 letters from her
  constituents about gun control
  
• A pollster asks 30 adults at the mall about their
  shopping preferences
  
• Fox News does a poll, and reports the opinions of
  the 2500 people who called in.
  
• Researchers test out a new cancer drug on 100 men
  with prostate cancer.

4
Parameters and Statistics

• A parameter is a numerical measurement describing
  some characteristic of a population
  
• A statistic is a numerical measurement describing
  some characteristic of a sample

5
Parameter or Statistic?

• Of the 350 letters read, 250 wanted more
  restriction on gun sales
  
• Of the 30 people questioned, 20 were shopping for
  themselves
  
• Americans spend 23 billion shopping online this
  holiday season.
  
• In the last election, 82 of registered voters
  voted in Washington

6
Qualitative/Quantitative

• Qualitative Data is data that only has qualities
  (categories or names), but no numbers
  
• Examples Eye color, Yes/No, type of car
• Quantitative Data is data that is a numerical
  quantity (a number, usually with units)
  
• Examples Height, weight, hours slept

7
Discrete and Continuous Data

• Discrete Data comes from a finite or countable
  set of possibilities.
  
• Example How many kids do you have? Possible
  answers are 0,1,2,, but not 1.3
  
• Continuous Data comes from an infinite set of
  possibilities
  
• Example Your car speedometer reading. It is
  possible to be going 20mph, 20.5mph, 20.01mph,
  etc.

8
Levels of Measurement

• Nominal all we have is names
• Ordinal we can also order
• Interval also, differences are meaningful
• Ratio also, ratios are meaningful

9
Whats the level of measurement?

• Salaries of corporate executives
• Your now serving number at the DMV
• Peoples area codes
• Record time for 100m dash
• Peoples birth state
• Daily low temperatures
• Birth years

10
Homework 1-2

• 1.2 1, 3, 5, 9, 11, 13, 15, 17