By Vaie Kokil
Statistics: Collection of methods for planning
experiments, obtaining data, and then organizing,
summarizing, presenting, analyzing, interpreting,
and drawing conclusions.
Variable: Characteristic or attri
Numerical Summary Measures
What is a
Quantitative variables are recorded as numerical
values. They are measurements or counts taken on
each unit in the sample.
Consider the following examples:
1. Age of a person.
A Problem-Solving Approach
Example: Buckle Up
Two drivers on the Pennsylvania
Turnpike are selected at random and
checked for compliance with the
seatbelt law. How many possible
outcomes are there, and what
1. Construct the sampling distribution of a
2. Use the Central Limit Theorem to
compute probabilities involving sample
Construct the sampling distribution of a
Sampling Distribution of the Sample
Random Variables and
5.1 Random Variable
A random variable is a
function that assigns a
unique numerical value to
in a sample
their values cannot be predicted
1. Uniform distribution
2. Exponential distribution
3. Use a normal curve to describe a normal population
4. Find areas under the standard normal curve
5. Find z-scores corresponding to areas under the normal curve
6. Check fro normality
Tables and Graphs for
Tables, Charts, Graphs
Used to organize and summarize data.
1. Shape: skewed or symmetric.
2. Center: where is the majority of the data located?
3. Variability: spread, or dispersion, of the data; compact
Find critical values for confidence intervals
A point estimate of a parameter is the
value of a statistic that estimates the
value of the parameter.
A confidence interval estimate of a
parameter consists of an interval of numbers