1) are commonly known as numerical facts
2) is a field of discipline or study
Here, statistics is about variation.
3 main aspects of statistics:
1) Design (Think): Planning how to obtain data to answer questions.
Ch. 16 Random Variables
Defn: A random variable is a numerical measurement of the outcome of a random
A discrete random variable is a random variable that assumes separate values.
# of people who think stats is dry
The probability distribution
Ch. 7 Scatterplots, Association, and Correlation
So far, weve seen univariate data. This section, however, considers bivariate data and
how two numerical variables are related. Methods of description are introduced here and
formalized in Ch. 27.
Ch. 14 Introducing Probability
Defn: An experiment is a process that, when performed, results in one and only one of
many observations (or outcomes).
Probability is a numerical measure of likelihood that a specific outcome occurs.
3 Conceptual Approaches
Ch. 18 - Sampling Distributions
Expanded defn: A parameter is: - a numerical value describing some aspect of a popn
- usually regarded as constant
- usually unknown
A statistic is: - a numerical value describing some aspect of a sample
- regarded as rando
Ch. 19 - Statistical Inference
Defn: Estimation is the assignment of value(s) to a population parameter based on a
value of the corresponding sample statistic.
An estimator is a rule used to calculate an estimate.
An estimate is a specific value of an est
Ch. 23 CI for a Population Mean
- common situation is that is unknown, so the sample data must estimate it.
. We now have Z
Recall Z =
= t , where t is a diff. standardized variable.
The value of s may not be all that close to , especially
Ch. 24 - Comparing Two Population Means
1. The two samples are random and independent.
2. At least one of the following is also true:
i. Both samples are large (n1 30 and n2 30)
ii. If either one or both sample sizes are small, then both popu
Ch. 20 - Hypotheses and Test Procedures
Defn: A null hypothesis is a claim about a population parameter that is assumed to be
true until it is declared false.
An alternative hypothesis is a claim about a population parameter that will be true
if the null
Ch. 11 13 - Gathering Data
Defn: An observational study is a study where a researcher observes characteristics of
subjects in samples from populations of interest.
A retrospective study is an observational study in which subjects are selected and