Distribution of Sample Means
The distribution of the means of an infinite
number of samples of a certain size selected
from a population
Before, we talked about distributions of scores, but now
we are
examples
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Dr. Mine etinkaya-Rundel
Duke University
The General Social Survey asks: For how many days during the past 30 days was your mental he
confidence interval
(for a mean)
what is a confidence interval?
conditions
finding & interpreting
Dr. Mine etinkaya-Rundel
Duke University
A plausible range of values for the population paramete
required
sample size for ME
sample size vs. accuracy
Dr. Mine etinkaya-Rundel
Duke University
backtracking to n for a given ME
given a target margin of error, confidence level, and information on th
another introduction
to inference
review simulation based inference
review hypothesis testing framework
Dr. Mine etinkaya-Rundel
Duke University
remember when
promotion
gender
promoted
not promote
accuracy vs.
precision
confidence level
width of an interval
trade-offs
Dr. Mine etinkaya-Rundel
Duke University
confidence level
Suppose we took many samples
and built a confidence interval fr
PDF
A probability density function (pdf), is a function associated with a continuous random variable
Areas under pdfs correspond to probabilities for that random variable
To be a valid pdf, a function
sampling
variability & CLT
sampling distribution
CLT + conditions for CLT
demo
Dr. Mine etinkaya-Rundel
Duke University
sample
sample statistic
sample
sample statistic
sample
sample statistic
sa
examples
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Dr. Mine etinkaya-Rundel
Duke University
Suppose my iPod has 3,000 songs. The histogram below shows the distribution of the
lengths of t
Stat 280, Fall 2016
Chapter 2
Numerical summaries of data
1. What did we look for in a histogram?
2. Location
(a) mean. Show Section 1. Center of gravity. Sum of errors is 0.
(b) median. Show Section
Stat 280, Fall 2016
Homework, Chapter 4
Coin A has a 50% chance of coming heads on each flip. Coin B has a 75%
chance of coming up heads on each flip. We flip A twice and B twice. The
flips are indepe
Stat 280, Fall 2016
Homework, Chapter 2
Read in the data file data.csv. This data set contains one variable - x.
Note: a common error when using a data set with only one variable is
to use the data se
Stat 280, Fall 2016
Homework, Chapter 1
Solutions
Attention graders: the students answers do not have to be exactly the
same as mine. Please make sure you read and understand each question in
the assi
Stat 280, Fall 2016
Homework, Chapter 1
We are studying production of a candy; it is a small chocolate covered in
a hard shell. The candy comes in six different colors. We are looking at
the output of
Stat 280, Fall 2016
Homework, Chapter 3
File animal.csv contains (fictional) data about birthweight and gestation
period for a number of animals. The file also contains information about each
animals
0910
This is an R Markdown document. Markdown is a simple formatting syntax for authoring HTML, PDF, and
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When y
15.075J: Statistical Thinking and Data Analysis
Lecture 5: Statistical Tests
Instructor: Hoda Bidkhori
1/43
Example: fair coin?
We want to know whether our coin is a fair coin (whether the probability
15.075J: Statistical Thinking and Data Analysis
Lecture 4: Confidence Intervals
Instructor: Hoda Bidkhori
1/58
Study: Young, unemployed, and optimistic
41% of the public believes young adults (i.e. n
1.
Data Preprocessing
a Combining some categories with similar probability.
b.
c. The model has worse performance without OpenPrice.
d. H0:1=0;Ha:10
SincethePvalueislessthanthesignificancelevel(0.05),