9/26/2017
1
STATISTICS 110
Outline for today:
Go over syllabus and dates for the quarter
Overview of basic terminology
Cover most of Chapter 0
Overview of coverage in this course and in
Stat 111/202
Examples on White Board
1. Ex 0.4: Do students with higher GPA have a
better chance of getting into med school?
MedGPA includes Accept/Deny and GPA
2. Ex 0.6: Do financial incentives help people
lose weight? Randomly assigned to get
incentive or not (control group)
WeightLossIncentive4 and page 8.
Some Fundamental Definitions
•Population: All of the individual units about
which we want information
–Examples on white board
•Sample: Units for which we obtain data
–Examples on white board
•A variable: Something we measure (for sample)
or could measure (for population) on each unit
–Examples on white board
Types of Data (Variables)
•Categorical: Data consist of category names
– Male/Female (two categories = binary)
– Level of education (ordered categories = ordinal)
– Smoker/nonsmoker
– Opinion on an issue (favor, oppose, no preference)
– Admit status (for med school example)
•Quantitative: Data consist of numbers where
ordinary arithmetic makes sense
– Height, weight, GPA, number of siblings
More Fundamental Definitions
(Population) Parameter:
A number associated with a population
–Example: Proportion admitted to med school
for the population of applicants with GPA of at
least 3.5.
(Sample) Statistic:
A number associated with a sample
–Example: Proportion admitted to med school
for the observed sample of applicants with GPA
of at least 3.5.
Description or Decision?
How Data Are Used
•Descriptive Statistics: using numerical and
graphical summaries to characterize
a data set (and only that data set).
•Inferential Statistics: using sample
information to make conclusions about
a population.
•Models: Used to approximate the population
relationship between two (or more) variables.
This course is all about finding good models!
