2. What Is Statistics?
• Science of collection, organization, analysis and interpretation of
numerical facts
Gathering Analyzing
•Drawing Inferences
• Originally associated with government data (e.g., census data), the subject now has
applications in all the areas
3. Types of Data
Qualitative and Quantitative
Discrete and Continuous
Univariate and Bivariate
Raw and Tabulated
4.
5. Quantitative and Qualitative Characteristics
• Quantitative characteristic – one which can
be measured numerically (variable)
• Example: Height, Weight, Number of
Patients
• Qualitative characteristic – one which
cannot be measured numerically
(attribute)
• Example: Intelligence, Beauty
6. Discrete and Continuous Variable
• Discrete variable
• A variable which assumes only some specified values in a given range
• Example: Number of children per family, Number of seeds per bean pod
• Continuous Variable
• A variable which assumes all the values in the range
• Example: Height of persons, Weight of apples
1. Skin color of a person Quantitative/Qualitative
2. Age Continuous/Discrete
3. Number of children in a family Continuous/Discrete
4. Years of education Continuous/Discrete
5. Family Status Quantitative/Qualitative
6. Sales value of a drug Continuous/Discrete
7. # of Calls to the particular doctor….. Continuous/Discrete
8. Characteristic of a population Statistic/Parameter
9. Nominal Scale
• Named categories
• Examples: Gender, Race, Party Identification, Place of Birth, Major Department
• Question: Before I begin, can I verify what is your specialty?
1. General Practice, or
2. Family Practice, or
3. Primary Care, or
4. Internal Medicine
5. Other
• Measure used: Mode
10.
11.
12. Ordinal Scale
•All observations are ordered (ranked) from lower to higher, but we can’t
assign any meaningful uniform distance between the ranks
•Examples: job prestige, social class, high school class rank
•Question: Did the rep present the full information of the product to you?
• 1 = Very poor information coverage 5 = Very good information coverage
•Measure used: Median, Mode
13.
14.
15. Interval Scale
•We can specify equal distance between levels, but there is no fixed and meaningful zero
point
•Examples: IQ scores, degrees Fahrenheit, degrees Centigrade (Celsius), GREscores
•Measure used: Mean
16.
17.
18. Ratio Scale
•There is some meaningful zero point, allowing us to form ratios of one value relative to
another value
•Examples: income, census counts, years of education
•Question: Cost of treatment in a government hospital
•Measure used: Mean
19.
20.
21. Data based on variables
Univariate – 1 Measured & 1 Category dataset
Bivariate – 2 datasets –both measured
Multivariate – More than 2 datasets –all measured
Measured Data =Continuous Data – Interval/Ratio
Categorical Data = Nominal /Ordinal Data