Stat 121
Sampling Distributions
Moore chapter 11
1
KEY WORDS
Sampling distribution
Law of large numbers
Central limit theorem
STUNNING IDEAS
Sampling distributions are
approximately normal
Sample mean
Stat 121: Scatterplots and Correlation
Represent data visually: one measurement per
individual
Grouped individuals by categorical variable: compare
distributions of quantitative variable
E.g. Student
Stat 121: Describing Data
Natasha Mandryk
1
!Visualize distributions with stemplots
!Measures of centre: Median and mean
!Measures of spread: Interquartile range
!Visualize distributions with boxplot
Stat 121: Inference about
Two Population Means
Moore chapter 18
1
inference when is unknown
Confidence intervals
One-sample t test
Matched pairs design
t distributions, degrees of freedom
Critical va
Fuel economy ratings give the Prius a highway
mileage of 48 mpg. Deborah wonders whether
the actual highway mileage of her Prius is less
than that. She keeps careful records for 3000
miles of highway
MAKING SURE CONDITIONS ARE REALLY SATISFIED
REALITY MEETS CALCULATIONS
30
! Study investigates link between community service
and secure relationships
! Sample: 74 students
57 had done service work
Stat 121 Assignment 1 Summer 2013
Assignment Instructions
You may work alone or in groups of up to 3. If you work in a group, submit one paper with all
team member names on it.
Assignments must be sub
Stat 121:
Inference about a Population Proportion
Moore chapter 19
1
1.
The data are an SRS from the population.
2.
The population is at least 10x larger than the sample.
Ensures that standard deviati
STAT121
Assignment1
JishengLiu
12862132
1.
a)
Height
DegreePrgm
BA
Mean
Statistic
Std. Error
167.63 1.953
95% Confidence Interval Lower Bound
for Mean
Upper Bound
5% Trimmed Mean
Median
Variance
Std.
STAT121
Assignment1
JishengLiu
12862132
1.
a)
Height
DegreePrgm
BA
Mean
Statistic
Std. Error
167.63 1.953
95% Confidence Interval Lower Bound
for Mean
Upper Bound
5% Trimmed Mean
Median
Variance
Std.
Stat 121:
Two Categorical Variables
Moore chapter 22
1
How do we determine
whether there is a
relationship between
education levels and
views on capital
CATEGORICAL
punishment?
VARIABLES
2
Cant calcul
Stat 121
Introduction to Inference
Moore Chapter 14
1
a)
Gives a range of reasonable values for the level of
confidence.
b)
Gives a range of reasonable values for the sample mean.
c)
Gives a range of
a)
Drawing conclusions about a population mean based on
information contained in a sample.
b)
Drawing conclusions about a sample mean based on
information contained in a population.
c)
Drawing conclus
Stat 121:
Inference about a Population Proportion
Moore chapter 19
1
Count type data
Divides population into two groups
Smokers and non-smokers
University students and everyone else
Think yes/no: numb
Stat 121: Normal Distributions
Which one of the following is a FALSE statement about the
standard normal curve?
a)
b)
c)
d)
Its standard deviation can vary with different datasets.
It is bell-shaped.
Strong positive
association:
number of
firefighters at a
structure fire
total damage
caused by fire.
Photo credit Flickr/dvs. CC licenced.
Are firefighters bad?
1
Need to take into account to explai
Stat 121 Reading for Chapter 2 Describing Distributions with Numbers
Instructions: Read Chapter 2. Take notes as you go. Bring your notes to class.
Your notes should help you to answer the following:
Stat 121 Reading for Chapter 4:
Scatterplots and Correlation
Instructions: Read Chapter 4. Take notes as you go. Bring your notes to class.
Try to answer the following:
What is the difference between
Stat 121 Reading for Chapter 1 Picturing Distributions With Graphs
Instructions: Read Chapter 1, omitting the section on time plots. Take notes as you go. Try the practice
problems at the end.
Your no
Stat 121 Reading for Chapter 3 The Normal Distributions
Instructions: Read Chapter 3. Take notes as you go. Bring your notes to class.
Try to answer the following:
How is a density curve related to a
Discuss/compare measures of centre and spread
Compare distributions using centre and spread
Discuss density curves and normal distributions
Estimate proportions of normally distributed populations
Tod
MUDDIEST POINT
1
Count
Minimum Value
Maximum Value
Range
40
5.00
10.00
5.00
Average
Median
Standard Deviation
Variance
8.45
9.00
1.24
1.55
Last days activity statistics
2
Stat 121: Normal Distribution
tinyurl.com/stat121survey
(alternative paper form at front of room)
Class Survey May 2013
Stat 121:
Representing Data
Natasha Mandryk
Flickr: Jerry Oldenettel
Behrs Hairstreak
ID
Capture type easting
What questions
come to mind?
TOASTER
REGRESSION
1
Toast data: what do you see?
2
If a child has IQ 110,
what would you
predict his/her
reading score to be?
3
LINES OF BEST FIT
PREDICTING RESPONSE VALU
Stat 121
Introducing Probability
1
Which is a correct interpretation of the statement The
probability that a child delivered at KGH is a girl is 0.50?
a)
Over a long period of time, there will be equa
6/4/2013
HOW MUCH DID YOU SPEND
ON COFFEE YESTERDAY?
ANSWER HERE:
Stat 121
Sampling Distributions
Moore chapter 11
http:/tinyurl.com/stat121coffee
1
A random sample of 1600 people across Canada was as
Quiz 1 and Assignment 1 available for pickup
Assignment 2 due in class tomorrow
Lab quiz this week
For tomorrow:
Read ch 89 (qualitative)
Think about how you would design an experiment to test the
e
Stat 121
Introducing Probability
1
KEY WORDS
4 laws of probability
Normal probability
Sampling distribution
Law of large numbers
Central limit theorem
STUNNING IDEAS
Normal curve is really a
probabili
Stat 121 Reading for Chapter 5 Regression
Instructions: Read Chapter 5. Take notes as you go. Bring your notes to class.
Try to answer the following:
How are regression and correlation related?
What k