Honors Statistics Aug 23-8:26 PM Daily Agenda 1. Check homework C4#2 Aug 23-8:31 PM 1
Apr 6-9:53 AM 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 2
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 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 3
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 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 4
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 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 5
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 Name the undesirable methods used to obtain a sample from a population. Oct 26-4:55 PM 6
Nov 7-10:17 AM Oct 26-4:54 PM 7
involves studying a part in order to gain information about the whole. Sampling Frame methods of sampling probability sampling simple random sampling (SRS) stratified random sampling cluster sampling systematic random sampling multistage sampling voluntary response convenience sample 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 Picking a Sample... Names out of a hat Label Random Rules Identify Oct 27-3:08 PM 8
Oct 26-5:04 PM Do different sizes of tickets example with class. Is this fair? Mar 12-11:13 AM 9
Oct 31-12:19 PM Mar 17-9:33 AM 10
Nov 1-7:33 PM Oct 31-12:11 PM 11
Example on page 217 Label: Identify sample: Oct 26-5:09 PM Using Technology Seed Calculator first 323 Rand Identify Oct 26-5:11 PM 12
Using the calculator to select random numbers. Choose a unique number between 5439 and 9127 Seed the calculator your number rand choose the sample of 5 words using the command randint (1,130,1) do not use repeats Mar 12-10:54 AM 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: 084 214 475 377 377 287 447 559 208 563 791 409 245 453 645 668 126 142 147 836 126 091 537 398 481 145 926 Apr 5-5:16 PM 13
117 Rand Identify Oct 26-5:11 PM Oct 26-5:17 PM 14
First "random" sample Circle 5 random words. Oct 27-3:45 PM Oct 24-7:24 AM 15
Using a random digit table to select random numbers. We must think of the numbers as three digits 001 to 130 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 130, do not keep repeats. Mar 12-10:54 AM Oct 31-12:11 PM 16
Oct 28-3:05 PM Block 3 Student Sample Random Sample Random Sample 2 3 4 5 6 7 8 Oct 27-3:19 PM 17
Block 1 Student Sample Random Sample Random Sample 2 3 4 5 6 7 8 Oct 27-3:19 PM Type of sampling method? LABEL: TABLE: STOPPING PROCEDURE: IDENTIFY SAMPLE: LABEL: TABLE: STOPPING PROCEDURE: IDENTIFY SAMPLE: Apr 5-5:25 PM 18
Put numbers on homework tables of names line 107 QUIZ ON CHAPTER 4 SECTION 2 NOTES MONDAY Apr 6-9:53 AM 19