- Frequency and Cumulative Frequency
- Symmetry and Skew
- Mean and Median
- Which is best?
- Video: The mean
Frequency and Cumulative Frequency
- A frequency distribution, like a histogram shows the number of
observations in a part
Using correlation to see if paired
Begin Chapter 11: The regression equation.
Problem 10.19: Do reading and television viewing compete for
leisure time? We have a random sample of 10 children with
X: Books read last year
SPSS on two independent samples.
Two sample test with proportions.
Paired t-test (with more SPSS)
State of the course address:
The Final exam is Aug 9, 3:30pm 6:30pm in B9201 in the
Burnaby Campus. (One or two hallways off from AQ on the
Formula for linear models.
Prediction, extrapolation, significance test against zero
Last time, we looked the linear regression formula.
Its the line that fits the data best. The Pearson correlation
can be considered a measure of how well that line
This time: A correction, ANOVA with review, student reviews.
Assignment 4 is marked and in the workshop.
Correction from Mondays lecture.
A more detailed account of why this is so is in Wk13_Extra on
webpage, but its for interest only.
What I said:
SPSS Demo: Entering data
SPSS Demo: Get the mean, median, histogram, skew
SPSS Demo: Putting graphs into word
Quartiles and the Five Number Summary
Read for today: All of Chapter 3 (Measures of Central Tendacy)
- The mean of 4,
- Independent samples
- Pooled standard devation
- The equal variance assumption
Last time, we used the mean of one sample to test against the
hypothesis that the true mean was a particular value.
Association and causation
Relevant text: P.54-60 Chapter 2
From last time:
- Boxplots are good for visualizing the general trend in
- They show everything in the _
- Regression example
- Multiple regression. SPSS for multiple regression.
- Prediction examples.
- Midterm is still being marked so no comment.
- The rest of assignment 4 is up, there are three questions for
marks. Due Wednesday at 4:30.
9 Lectures left W
SPSS: Expected frequencies, chi-squared test.
In-depth example: Age groups and radio choices.
Dealing with small frequencies.
Quick Example: Handedness and Careers
Last time we tested whether one nominal variable was
independent of another.
We did this by
Odds ratio, Odds ratio test for independence,
Assignment 5 is live on webpage. Due Wed Aug 1 at 4:30pm.
(9 days, 1 hour, 58.5 minutes)
Final exam is Aug 9.
Review session Aug 7? 8? What works for you?
Deadline for sug
Wed, June 26, (Lecture 8-2). Nonlinearity.
Significance test for correlation
R-squared, SSE, and SST.
Correlation in SPSS.
Last time, we looked at scatterplots, which show the
interaction between two variables, and correlation.
The correlation coefficient
STAT 203 Lecture 4-1.
The normal distribution is symmetric.
Getting the probability from between two z-scores
Translating standard scores to and from raw scores.
Extreme values beyond the table.
Text from last Friday:
Say a value X followed
Midterm 2, Question 2, 3, 4.
Odds. Odds Ratio.
Fractal by Emma Taylor.
Question 2: Test the null that the mean is 40 against the
= 46, s =6, n = 9
First, identify: We only have one sample mean, so this is a
_ .We are given that it
A full analysis example
New Dataset: Confidence
This is a dataset taken of the confidence scales of 41
employees some years ago using 4 facets of confidence
(Physical, Appearance, Emotional, and Problem Solving,
My friend Dave has terrible luck. He bought a computer, and
within 11 months (still under warranty) he had replaced the
heat sink, fans, and media button bar (twice),
hard drive (four times!)
and his company loyalty.
- Midterm Practice Problems Today!
Q1: Describe this distribution.
Q2: Statistic or Parameter
Describe this distribution
Use the checklist:
where is the middle, if applicable
Spread: how far from the middle does d
Samples can vary
From last time: A sample is a small collection we observe and
assume is representative of a larger sample.
Example: You havent seen Vancouver, youve seen only seen a
small part of i
What is inference?
Hypothesis tests in t
This weeks lectures are actually a combination of chapter 6
and chapter 7 material.
Knowing something about a sample, on its own, isnt very
Information about the population as a whole is much more
Welcome to STAT203 Statistics for Social Sciences
How to win at statistics.
Ch. 2 start: Nominal, Ordinal, and Interval data.
Video: Joy of Stats - Florence Nightingale
My Assumption is at the beginning of the semest
This time: ANOVA examples, course wrap-up.
ANOVA/Review example: We have a zombie outbreak. Weve
identified the cause: the nefarious Bayes Virus.
So far, we have five possible treatments were testing by
administering them to 40 petri dishes of infected bl
T-test in SPSS
Hypothesis tests of proportions
Confidence Intervals (End of chapter 6 material)
Definition of p-value:
The probability of getting evidence as strong as
you did assuming that the null hypothesis is true.
A smaller p-value means that its les
- Inter-Quartile Range,
Reading for today: Start Chapter 4.
Quartiles and the Five Number Summary
- The five numbers are the Minimum (Q0), Lower
Quartile (Q1), Median (Q2), Upper Quartile (Q3),
and Maximum (Q4).
- Q1 means b
More examples with probability
The normal distribution
Probability and the normal distribution
You should be about halfway through Chapter 5 by now.
(For assignment as well)
The probability rules.
Probability = ways event occurs
Identify the appropriate test
One proportion test
Two samples independent
Two samples paired
Estimate the correlation
What test should you do? Example 1
You want to find if more than 90% of skytrain users have valid
Type I and Type II Errors
Talk to your kids about p-value, or someone else will.
p-value: If H0 is true, what would the chances of observing as
much evidence as we did?
If the p-value is small, then the observed statistic is very
We took a survey of people in four career fields and found if
they were left or right handed.
These are the observed counts.
Most of the respondents are right handed except for in the
athletics field, where a few more than half are left handed.
We want to
This time: Some ANOVA theory, two large examples.
Last time, we started on ANOVA, or AnOVa, which is short for
Analysis Of Variance.
AnOVa is a set of statistical methods designed to answer one
question Where is the variance coming from?
A less formal way
A few more notes about Z
SPSS and the normal curve
Chapter 6: Samples vs. Populations
Convenience/accidental sampling: why online polls suck
Last day, we looked at the relationship between standard
scores (z-scores) and raw scores.
For example, if the a
Stat 1181 Notes: Unit #17 Hypothesis Testing or Tests of Significance
Review of Notation/Symbols
Sample Standard Deviation
Population Standard Deviation
The average/mean of a sample
Today: Dummy variables.
Dummy variables in a multiple regression, regression wrap up.
Looking back in regression, weve looked at how an interval
data response y changes as an interval data explanatory
variable x. Changes.
Example: Number of books read (y)
One more example of a hypothesis test
Chapter 10: Scatterplots
If time: Joy of Stats 200 Countries, 200 Years
You should know this.
You should be familiar with all of this, but dont waste
too much time memorizing.
Alzhiemers Onset and Gender (From Ch.7 ex
Stat 203 Additional (FOR INTEREST) material.
You are not responsible for knowing this.
Weve been looking at the Pearson correlation r without
looking at how its calculated.
For correlating the response variable to multiple explanatory
variables, the easie
Todays Agenda Wrapping up Ch.3 and 4
Mean and frequency (Loose end Ch. 3)
Variation (Not in text)
Standard Deviation (Ch.4)
Standard Deviation and Outliers (Ch. 4)
Consider the data set cfw_0,0,0, 4,4,7,10,10,10,10, n=10. Recall
that we could find the m
- Common problems from assignment 1. Q1,2,3,4.
Question 1. Consider the data set cfw_15, 9, 7, 20, 4, 12, 8, 0, 31
1f: Determine if this distribution is positively or negatively
skewed. How do you know this works?
Common question: How do we know if