STAT 103a
Homework #7
Investigate the relationship between Cereal Variables and per capita GNP (use regression to determine factors
which predict log(GNP/capita)
1. Identify variables, response & pred
STAT 103: Homework #3
1. random: unbiased (every sample of size n has equal chance of being selected) & independent (selection
of 1 unit has no influence on the selection of other units)
systematic: t
Examples :
PROBABILITY
Discrete
Chapter 3 in Cartoon Guide
STRONGLY RECOMMENDED
Toss a coin:
S = cfw_H,T.
Watch a tree for a year and see if it dies :
Probability is crucial to statistical inference
STATISTICS
We are given the following data:
Number of businesses: n = 43
Population proportion: = 0.31
Sample proportion: = 0.19
Level of significance: = 0.01
Null and alternative hypotheses are:
0 :
Hi, I hope this helps! Good luck
Explain the trend of the natural rate of unemployment in the US.
Natural rate of unemployment is, by definition, a combination of frictional, structural, and
surplus
Bruno Jednaak, STAT 103, HW4
1.
(a) Statistical model: Binomial
Each individual question represents one Bernoulli Trial (only two possible outcomes
right or wrong). As there are 15 questions, this me
Bruno Jednacak, STAT 103, HW1
Study finds that well-designed classrooms boost
student success
New research published by Salford University has suggested that the layout, construction and
design of cla
Bruno Jednacak, STAT 103, HW3
1. The sampling used are the following:
(a) Systematic sampling
Because every fifth driver is interviewed.
(b) Clustered sampling
Because population is first divided into
Bruno Jednaak, STAT 103, HW5
1. (a) According to the poll, the proportion of Democrats that support sending ground troops is:
115
296
= 0.3885 = 38.85%
The proportion of Republicans that support sendi
Bruno Jednacak, STAT 103, HW8
MONKEYS PROBLEM
(a) Using MINITAB, we make boxplot showing the distribution of correct choices by
treatment group.
Boxplot of Score (of 20 trials)
20
Score (of 20 trials)
Bruno Jednacak, STAT 103, HW6
1. (a) In order to answer this question, we are going to use the following graph:
For the first part, we are just going to look at the scatterplot of the data and the reg
Bruno Jednacak, STAT 103, HW2
1. Below is the scatterplot of the following data: cellphone use (per 100 people) and internet access
(percent of population).
Scatterplot of Cellphone vs Internet
200
Ce
Bruno Jednaak, STAT 103, HW7
Problem 2: GNP and Cereals by Country
I am going to examine the relationship between Cereal Variables and per capita GNP using
regression.
STEP 1: Identifying variables
Ou
Madison Bickel
Introduction to Statistics: Homework #1
Stat 103
1. Analysis finds California Students attend school more than U.S. Peers (L.A.
Times)
http:/www.latimes.com/local/education/la-me-school
Madison Bickel
TA: Michelle Roh
Hw #5
1. a. There was 75% support from Republicans and 30% support from Democrats.
Therefore, the poll estimated the difference in support to be 45%.
b. Using Minitab,
Sampling and Experiments
If in doubt, consult with a Statistician : you can save
immense heartache, loss of resources, etc. by checking
with an expert first!
Research Design : Some General Advice
De
Example :
Brain/Body weight
relationship in
mammals. Last time
we used regression
on the logs of brain
and body weight :
Once Again the simple linear leastsquares regression model :
y b0 b1 x
Simple L
Scatterplot Notation :
Data Relationships
The Horizontal axis is ALWAYS
called the X axis.
Today: describing relationship of two
quantitative variables :
Y
The Vertical axis is ALWAYS
called the Y a
Probability in Practice
(The trick is knowing when to apply which probability rule!)
Probabilities of events so far only add to 73% or 81%, investigation reveals that we forgot the last category (Not
Probability Models for Count Data
Bernoulli Random Variables
Example : Evolution vs. Creationism. A
Gallup poll conducted in 2008 (sample size n
1000 people nationwide) found that 44% of
American adu
Central Limit Theorem Interpretation 1
The Central Limit Theorem
Revisited
Take sample of size n from any distribution and calculate
the sample mean. Repeat this process many times. As
Two more views
Example : IQ Tests.
The general population has a mean
IQ score of 100 and the population
standard deviation of scores is
16 .
Hypothesis Testing
Like proof by contradiction : (think back to geometry
Boxplot of illiteracy by Gender
Pooled Standard Deviation Estimate
50
40
30
Rate
Example : World Poverty Data,
2000. Compare worldwide illiteracy rates
between men and women at the 99%
confidence leve
Theoretical Regression Model
Inference for Regression
(Return of the Regression!)
Mean of Y is a linear function of X.
Inference for Regression answers questions like
Y o 1 X
How strong is the evid
Test for the correlation coefficient
Announcements
Midterm Thursday, 10/21 in OML202
(rho or row) is the true correlation,
estimated by r the sample correlation
Closed note, closed book. Any compli
Introductory Statistics 09-01-11
Statistics
o Quantifying variation
o Distinguishing fact from fiction (e.g. firefighting is not the most dangerous
occupation)
o Collecting, organizing, & interpreting
Introductory Statistics 09-06-11
Mean
o The average
o The balancing point
o Add all data together then divide by how many things you added
Median
o For odd # of observations, its the middle one
o For