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. What’s 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. What’s the level of measurement?
Salaries of corporate executives
Your “now serving” number at the DMV
People’s area codes
Record time for 100m dash
People’s birth state
Daily low temperatures
Birth years

10. Homework 1-2
1.2: 1, 3, 5, 9, 11, 13, 15, 17