Chapter 23 notes 11­12
2/27/12
AP STATS
Warm­up: What is a z-score?
EQ: What is a t­score?
HW: pg 541 1, 2, 6, 7, 12, 21, 25, 26, 28
Due 3/2
1
Chapter 23 notes 11­12
Feb. 27, 2012
HW: pg 541 1, 2, 6, 7, 12,
21, 25, 26, 28
EQ: What is a t­score?
Chapter 23: Day 1
t­scores:
Similar to z­ scores except we use t when dealing with problems that use the mean values.
Formulas:
2
Chapter 23 notes 11­12
Differences between t and z:
#1: t is for means...z is for proportions
#2: t­scores use degrees of freedom(df )
df = n ­1 or the sample size ­1
#3: pt ­values are slightly bigger
#4: Can't use the 68­95­99.7 rule with t if the degree of freedom is too low (**100>n)
#5: Margin of error is bigger with t
#6: If you know σp, use z; if you use 's' to estimate the standard deviation, use t.
3
Chapter 23 notes 11­12
Finding p­values on calculator:
2nd Vars (DISTR) tcdf
(min t­score, max t­score,degree of freedom)
Examples: 1.) t= 2; df = 12 .0343
2.) t= ­1; df = 20
.165
3.) t=0.5 and 1.645; n= 6
.239
4
Chapter 23 notes 11­12
Finding critical
values:
(Finding t)
2nd Vars (DISTR) Invt
(confidence %, df)
Examples: 1.) co= 95%; df = 4 2.) co= 68%; n = 10
3.) co= 80%; df= 6
t= 2.132
t= .482
t= .906
5
Chapter 23 notes 11­12
2/28/12
AP STATS
Warm­up: What is a t-score?
EQ:
What is the nearly normal condition?
HW:
pg 541 1, 2, 6, 7, 12, 21, 25, 26, 28
6
Chapter 23 notes 11­12
Feb. 28,2012
HW: pg 541 1, 2, 6, 7, 12,
21, 25, 26, 28
Nearly normal condition:
Calculator:
EQ: What is the nearly normal condition?
Chapter 23: Day 2
The distribution of the data is unimodel and symmetric. You can claim that the data is nearly normal. Draw/create a histogram to check.
To make a histogram, enter data in L1.
2nd y= then choose plot 1
To see graph, zoomstat
Example:
Data of mean car speeds on a neighborhood roads:
29, 34, 34, 28, 30, 29, 38, 31, 29, 34, 32, 31, 27, 37, 29, 26, 24, 34, 36, 31, 34, 36, 21
7
Chapter 23 notes 11­12
1-sample t-interval
test:
y ± t* x SE (y)
Confidence interval
Calculator steps:
margin of error
Stat
test
Data
If you have the table of
data; select and choose the list it's under. Then
calculate.
8: Tinterval
Stats
If you have the stats from the question. Enter the info and calculate.
8
Chapter 23 notes 11­12
1 Sample t-test:
Hypotheses Tests
Calculator steps:
Remember Ho and HA must be created to perform this test.
Stat
test
2: t-test
If you have the table of
data; select and choose the list it's under, decide the
direction of the data and calculate.
If you have the stats from the question. Enter the stats, decide the direction of the data and calculate.
9
Chapter 23 notes 11­12
The Watch list
Do not confuse proportions and means.
Beware of multimodal, skewed data.
Outliers will cause problems. You may need to do the test twice. Once with the outlier and one time without it.
10
Chapter 23 notes 11­12
2/29/12
AP STATS
Warm­up: Name 1 difference between z and t.
EQ:
Do you understand how t-tests work?
HW: pg 541 1, 2, 6, 7, 12, 21, 25, 26, 28
11
Chapter 23 notes 11­12
2/29/12
HW: Pg 541 1, 2, 6, 7, 12, 21, 25, 26, 28
Due 3/2
EQ:Do you understand how t-tests
work?
Chapter 23: Day 3
Class work Problems: 15, 17, 27, 31
12
Chapter 23 notes 11­12
2/29/12
AP STATS
Warm­up: Anything about t­tests you are still confused on?
EQ:
Do you understand how t-tests work?
HW: Study for the test
13
Chapter 23 notes 11­12
3/02/12
AP STATS
Warm­up: Get out review
EQ:
HW:
Do you understand how t-tests work?
Practice AP Test Due Friday
14
Chapter 23 notes 11­12
???
HW: pg 541 1, 2, 6, 7, 12,
21, 25, 26, 28
EQ: Do you understand how t-tests work?
Chapter 23: Lab
Lab: Are you Smarter than a 5th Grader?
Log on to the navigators.
Prgm Gonavnet Enter first name last initial network apps learnchk Smarter than a fifth grader
Answer the questions. Make sure you document how confident you were of your answers. Ho: μyou =μfifth grader
>μfifth grader
Ha: Hμoyou
and H
A
15