1. An Introduction to Statistics

2. What does a statistician do?
A statistician makes sense of information collected about the world
Analyze effectiveness of drug treatments
Determining behavior patterns
Analyze spread of West Nile Virus
Analyze performance of individuals, businesses, stocks, etc.

3. What is statistics?
Statistics is a branch of mathematics dealing with the collection, analysis, interpretation, and presentation of masses of numerical/categorical data.

4. What is statistics?
Statistics is a way of reasoning together with collection tools and methods designed to help us to understand data and information about the world.

5. What are statistics?
Calculations made from data.

6. What are data?
Systematically recorded information together with context

7. Context Tells: Who was measured What was measured
Where data was collected
When data was collected
Why study was performed
How data was collected

8. Data can be...
Numbers
Dates
Words
Codes or other labels

9. What is univariate data?
one
variable
the major purpose of univariate analysis is to describe one variable
central tendency: mean, mode, median
variability: range, max, min, quartiles, standard deviation
graphs: histogram, box-and-whisker plot  

10. What type of data is it? vs. Qualitative Quantitative
Deals with descriptions.
Data can be observed but not measured.
Colors, textures, smells, tastes, appearance, beauty, etc.
Deals with numbers.
Data that can be measured.
Length, height, area, volume, weight, speed, time, temperature, cost, ages, etc.
Go over the Collect student data worksheet and discuss which type of variable each one is.

11. Qualitative (Categorical) Variable
Is a classification or categorization
Something that is a name, word, or code
Examples:
Name of country
Type of shoe
Class year
Area code

12. Quantitative Variable
Is a measurement, amount, or count
Can by indicated by words “amount” or “number of”
Examples:
Height
Amount of time spent studying
Distance traveled
Amounted of money in your wallet

13. Ordinal Variable Is an ordered rating or ranking Examples:
Course grade
Class rank
Customer service rating

14. Caution! A thing is not a variable.
Shoes are things. The type of shoes is a qualitative variable. The number of shoes is a quantitative variable.

15. Quantitative Variables
Quantitative variables can be discrete or continuous.

16. Discrete Quantitative Variables
A quantitative variable is discrete if the variable involves a count (no decimals/fractions).
Examples:
Number of students
Number of shoes
Number of bills in your wallet

17. Continuous Quantitative Variables
A quantitative variable is continuous if the variable involves a measurement.
Examples:
Height
Distance traveled
Weight of a box

18. Caution!
Important to consider what values mean and how they are being used
Do not treat all numerical data as quantitative
The average of qualitative data is meaningless (example: the average zip code)

19. Example 1: Quantitative or Qualitative?
Number of students in a class who turn in a project before it is due.
Gender of the next baby born at a hospital.
Amount of fluid ounces dispersed by a soda machine.
Thickness of the gelatin coating on a pill.
Birth order (oldest, middle, youngest) of a student.

20. Homework Pick 10 items in your home.
Describe 5 of these items quantitatively. Provide three different descriptors for each item.
Describe the other 5 items qualitatively. Provided three different descriptors for each item.
This will be collected for a homework grade tomorrow.