Chapter 4 Section 1 day 2 2016s Notes.notebook
March 17, 2016
Honors Statistics
Aug 23-8:26 PM
Daily Agenda
3. Check homework C4#2
Aug 23-8:31 PM
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Chapter 4 Section 1 day 2 2016s Notes.notebook
March 17, 2016
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Apr 6-9:53 AM
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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All the artifacts discovered at the dig.
Actual Population - Due to the random sampling ...
All the artifacts discovered at the dig.
The 2% of the artifacts randomly chosen from those
discovered at the dig.
Oct 26-2:42 PM
The 1000 envelopes stuffed by the
automated machine each hour.
Actual Population - Due to the random sampling ...
All of the 1000 the envelopes.
The 40 envelopes sampled at random from the
Oct 26-2:55 PM
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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The 45,000 people who made credit
card purchases at the department store.
Actual Population - Due to the random sampling ...
All the 45,000 people.
Sample - Sadly only the 137 people who returned the survey.
BIAS SAMPLE
WHY?
Oct 26-2:56 PM
I am not convinced that a majority of the
voters oppose the bill. This is a voluntary
sample of her constituents.
I would explain to the congresswoman that
because of the voluntary nature of the
sample there is a bias present. Usually
people with strong opinions are the ones
motivated to write to their representatives.
This sample systematically favors the
"oppose" opinion and should not be used to
judge the true beliefs of her constituents.
Oct 26-2:56 PM
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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This is a voluntary response sample and it will
over represent the opinions of those who feel
most strongly about the issue being surveyed.
Perhaps it was a poll posed just after a
woman's professional sports win, a very
exciting game so many were thinking about
this event and thus in favor of equal pay.
Oct 26-2:56 PM
This is a convenience sample and it will
represent the opinions of those who were
If it was during daytime shopping hours then it
could over-represent those who do not have a
job and have more time to shop than those
who are employed.
Oct 26-2:56 PM
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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This is a convenience sample and it will
represent the opinions of those who were
available for the survey, the students who
were first to arrive at school.
This sample is biased because it will over
represent the students who arrived at school
first. Perhaps these students needed to get up
earlier than the rest and so they did not get as
much sleep than the others. 7.2 is less than
the average.
Oct 26-2:56 PM
This is a voluntary response sample.
This sample is biased because it will over
represent those with strong opinions on the
cell phone issue. Probably people who have
been in an accident caused by cell phone use.
I believe that 85% is probably higher than the
true population percent of all adults who
believe that cell phone used while driving
should be banned.
Sadly, many people still use their cell phones
while driving.
Oct 26-2:56 PM
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Name the undesirable methods used to
obtain a sample from a population.
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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involves studying a part in order to gain information
about the whole.
methods of sampling
probability sampling
simple random sampling (SRS)
stratified random sampling
cluster sampling
systematic random sampling
multistage sampling
voluntary response
convenience sample
Sampling Frame
A sampling frame is the LIST of individuals from which a sample is selected.
This list should include all of the intended population of interest.
Apr 5-5:13 PM
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Picking a Sample ... Names out of a hat
Label
Random
Rules
Identify
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Do different sizes of tickets example with class.
Is this fair?
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Example on page 217
Label: Use 2 digit numbers
start on line 131 and choose
Identify sample:
00 71 66 32 81
41 48 73
78 55 76 45 19 59 65 65 68 73
05 Beach Castle
19 Sea Castle
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Using Technology Seed Calculator first
323
Rand
Identify
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Suppose that your are a regional manager in charge of all
the WalMart stores in NYC that sells your company's
LABEL: (N)
STOPPING PROCEDURE:
084
214
475
377
377
287
447
559
208
563
791
409
245
645
668
126
142
147
836
126
091
537
398
481
145
926
453
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Chapter 4 Section 1 day 2 2016s Notes.notebook
117
March 17, 2016
Rand
Identify
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117
Rand
Identify
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FINISH ACTIVITY
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Using a random digit table to select random numbers.
We must think of the numbers as three digits 001 to 150
Pick a random starting place...
choose the sample of 5 words by "peeling off" three
digits at a time. Only keep 3 digit numbers between
001 and 150, do not keep repeats.
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Oct 31-12:11 PM
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Blocks 1, 2, and 4
Student Sample
Random Sample
Random Sample
2
3
4
5
6
7
8
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Type of sampling method?
LABEL: Use 2 digit numbers from 01
30
to 30.
4
TABLE: Start on line 145 and choose
2 digit numbers.
STOPPING PROCEDURE: Continue until 4 DIFFERENT
2 digit numbers between 01 and 30 are selected.
IDENTIFY SAMPLE:
19 = Miranda
26 = Santos
06 = Elashoff
09 = Griswald
LABEL: Use 1 digit numbers from 1 to
10
0 with 0 = 10.
2
TABLE: Start on line 123 and choose
1 digit numbers.
STOPPING PROCEDURE: Continue until 2 DIFFERENT
1 digit numbers between 1 and 0 are selected.
IDENTIFY SAMPLE:
5 = Kim
5, 4
4 = Gupta
Apr 5-5:25 PM
Put numbers on homework tables of names
line 107
QUIZ ON CHAPTER 4 SECTION 2 NOTES
TOMORROW
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Use two digit numbers from 01 to 40
Start at line 107 choose two digit numbers.
Continue until 5 DIFFERENT two digit numbers
from 01 to 40 are selected
82 73 95 78 90
81 67 65 53 00 94
Sample consists of the following classmates.
Johnson (20)
Rider (31)
Calloway (07)
Oct 27-7:07 PM
Use two digit numbers from 01 to 33
Start at line 117 choose two digit numbers.
Continue until 3 DIFFERENT two digit numbers
from 01 to 33 are selected
79 85
Sample consists of the following complexes
Fairington (16)
Fowler (18)
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Oct 31-12:11 PM
Use numbers from 1 to 1410
Seed Calculator with number 222 (just for classroom
purposes)
RANDOM: Use calculator command to generate random numbers
RANDINT(1,1410,1)
Continue until 141 DIFFERENT numbers
from 1 to 1410 are selected
Sample consists of the following plots. (do only first 3)
Oct 27-7:09 PM
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Use numbers from 1 to 55,914
Seed Calculator with number 555 (just for classroom
purposes)
RANDOM: Use calculator command to generate random numbers
RANDINT(1,55914,1)
Continue until 395 DIFFERENT numbers
from 1 to 55914 are selected
Sample consists of the following gravestones.(do only first 3)
gravestones 43962, 1387, 4182
Oct 27-7:09 PM
the theoretical probability of four 0 in 40 digits is
exactly 4 but this will not always occur with a "random" sample
of 40 digits.
with 10 digits possible there is a 1/100
chance of two digits being 00 (or 100)
, this will not happen very often but there is a chance that
four digits could be the number 0000. One out of 10,000 chance that
it will occur. ALSO, this number 0000 is just as likely as any other 4
digits!! Think about it.
Oct 27-7:10 PM
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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Picking the same "Random" sample each time will not
result in your samples being "Random" any longer....
Oct 27-7:10 PM
To find the sample of 20 randomly selected phones might be a
problem if you waited until the end of the day. Perhaps the managers
could select 20 numbers from 1 to 1000 ahead of time. But then you
would not want to tell the people manufacturing the phones which ones
were selected for inspection ...
b) The last 20 phones are not a random sample so Bias could result.
Perhaps the last 20 phones are of poorer quality than the first phones
manufactured. Tired people or tired machines (over heated, etc.) could
result in the ending phones not having the same quality.
This is NOT a Simple Random Sample because all possible groups
of 20 phones would not be equally likely to be selected. It would be
impossible (probability = 0) for the 20 phones in a row to be selected.
Perhaps 20 phones in a row might be a desirable group occasionally.
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Chapter 4 Section 1 day 2 2016s Notes.notebook
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It would take a very long time (and time is money) to count
and label all of the trees in the Rocky Mountain National Park.
An SRS is not a pratical way to sample in this setting.
sample could result in a bias sample. Perhaps the car
emissions are contributing to the trees dying and would
produce a result that overestimates the dead trees.
c) Scientists should not conclude that exactly 35% of all pine trees on the
west side of the park are infested because the sample yielded 35%. If the
sampling method was carried out correctly they should have confidence
that the approximate tree infestation is 35%. Sampling variability is the
concept that each time a sample is selected it could result in different
estimates of the true population "answer". These estimates should only
slightly vary with proper sampling techniques.
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