Stats

When you drop your pencil point blindly into the middle of a table of random digits, what is the chance that the three digits to the right of where you land will be 999?

1 in 1000, because every three-digit group has the same chance to come up.

Results of a verbal SAT were normal with a mean of 480 and std dev of about 100. What percent scored above 580?

16%

If Jennifer's score was 2 std devs above the mean, what percent of scores are higher than hers?

2.5%

The distribution of heights for adult males are normal w a mean of 69 inches and std dev of 2,5 inches. ABout what % are shorter than 64%?

2.5%

The distribution of heights for adult males are normal w a mean of 69 inches and std dev of 2,5 inches. What % of men are taller than 74 inches?

2.5%

5 number summary of students who took an exam: 18, 39, 62, 76, 100. Total of 416. How many scored above a 39?

312

5 # Sum ( 5, 18, 20, 40, 75) If any outliers existed, what would be the maximum length possible for a the right side of the whisker?

33

A man whose z-score was 0.3 is at the 61.79th percentile. What percent of all men are taller than him?

38.21%

The heights of 99.7% of men are between 5'0 and 7'0. What is your estimate of the Std Dev?

4 inches

Results of a verbal SAT were normal with a mean of 480 and std dev of about 100. The median score was..?

480

BAsed on shape of the distribution, what numerical measures would describe it?

5 # summary

The telephone company says that 62% of all residential phone numbers in Los Angeles are unlisted. A telephone survey contacts a random sample of 1000 Los Angeles telephone numbers, of which 58% are unlisted. In this setting,

62% is a Parameter and 58 is a statistic

Results of a verbal SAT were normal with a mean of 480 and std dev of about 100. What percent scored between 380 and 580?

68%

A table of random numbers is used to select 30 kids from a class. These 30 students are...?

A SRS of the class

The next five questions concern this situation: Do doctors in managed care plans give less charity care? Researchers chose 60 communities at random, then chose doctors at random in each community. In all, they interviewed 10,881 doctors. Overall, 77.3% of the doctors said they had given some care free or at reduced rates because of the patient's financial need in the month before the interview. Doctors who received at least 85% of their practice income from managed care plans were significantly less likely than other doctors to provide charity care. SOME DOCS WHO DIDN'T GIVE CARE MAY LIE. WHAT WOULD THE STUDY SUFFER FROM?

bias: the sample result will systematically overestimate the true percent of doctors who give charity care

The next five questions concern this situation: Do doctors in managed care plans give less charity care? Researchers chose 60 communities at random, then chose doctors at random in each community. In all, they interviewed 10,881 doctors. Overall, 77.3% of the doctors said they had given some care free or at reduced rates because of the patient's financial need in the month before the interview. Doctors who received at least 85% of their practice income from managed care plans were significantly less likely than other doctors to provide charity care. THE PEOPLE WERE SELECTED USING?

A stratified sample

In a table of random digits...

Any pair of entries is equally likely to be any of the 100 possible pairs

BLANK A in a sampling method means that the sample results will systematically misrepresent the population in the same way when we take repeated samples. For example, if we contact only people listed in telephone directories, the sample suffers from BLANK B. If some people chosen for the sample refuse to participate, the sample suffers from BLANK C. Both BLANK B and BLANK C are common sources of BLANK A. WHAT IS BLANK C??

Nonresponse

The next five questions concern this situation: Do doctors in managed care plans give less charity care? Researchers chose 60 communities at random, then chose doctors at random in each community. In all, they interviewed 10,881 doctors. Overall, 77.3% of the doctors said they had given some care free or at reduced rates because of the patient's financial need in the month before the interview. Doctors who received at least 85% of their practice income from managed care plans were significantly less likely than other doctors to provide charity care. THIS STUDY IS A?

Observational Study

A table of random numbers is used to select 30 students from a statistics class to rate a statistics video. The ratings that these students give are used to estimate the ratings that would be given if the entire class were asked to rate the video. The average of the ratings of all students in the class is

Population parameter

The next five questions concern this situation: Do doctors in managed care plans give less charity care? Researchers chose 60 communities at random, then chose doctors at random in each community. In all, they interviewed 10,881 doctors. Overall, 77.3% of the doctors said they had given some care free or at reduced rates because of the patient's financial need in the month before the interview. Doctors who received at least 85% of their practice income from managed care plans were significantly less likely than other doctors to provide charity care. THE NUMBER 77.3% IS A WHAT?

Stat bc is describes a sample

The student newspaper runs a weekly question that readers can answer online or by campus mail. One question was "Do you think the college is doing enough to provide student parking?" Of the 136 people who responded, 79% said "No." The number 79% is a

Statistic

MOst important advantage of experiments over observational studies...

The give good evidence for cause and effect

BLANK A in a sampling method means that the sample results will systematically misrepresent the population in the same way when we take repeated samples. For example, if we contact only people listed in telephone directories, the sample suffers from BLANK B. If some people chosen for the sample refuse to participate, the sample suffers from BLANK C. Both BLANK B and BLANK C are common sources of BLANK A. WHAT IS BLANK B?

Undercoverage

A local tax reform group polls the residents of the school district and asks the question, "Do you think the school board should stop spending taxpayers' money on non-essential arts programs in elementary schools?" The results of this poll are likely to

Underestimate support for arts programs because of non-sampling error.

in one of the first attempts to discover peed of light, newcomb made 66 measurements. why did he repeat it 66 times and why take the average of 66?

averaging measurements reduced impact of sampling variability

When taking a census we attempt to collect data from...

every individual in the population

Gallup conducts its polls by telephone, so people without phones are always excluded from the Gallup sample. Any errors in the final result due to excluding people without phones are..

in addition to the announced MOE

If the mean was 43 with a std dev of 4, what will happen if 5 is added to each number of the dist.

mean = 48 std dev = 4

500 m and f are asked about cellphone usage. This is an example of?

observational study

WHich statements are true about the std dev

s is always positive, and should be used to measure spread only when x is used as measure of center.

For distribution skewed to the left...

the median will be larger than the mean

An example of categorical is

the name of college and a students gender

Scotland is considering independence from the United Kingdom. An opinion poll showed that 51% of Scots favor "independence." Another poll taken at the same time showed that only 34% favored being "separate" from the United Kingdom. The reason these results differ by so much is that

the wording of questions has a big effect on poll results.

What is the MOE for a sample of 10,881

+/- 0.96

At what stage of the stats prob solving do you employ graphs and summaries?

Analyze Data

BLANK A in a sampling method means that the sample results will systematically misrepresent the population in the same way when we take repeated samples. For example, if we contact only people listed in telephone directories, the sample suffers from BLANK B. If some people chosen for the sample refuse to participate, the sample suffers from BLANK C. Both BLANK B and BLANK C are common sources of BLANK A. WHAT IS BLANK A??

Bias

Dot Plot of adult literacy rates in 177 countries. The lowest was 23.6% The shape of the distribution is

Clearly skewed to the left

500 m and f are asked about cellphone usage. The two variables?

Gender and # of text messages

500 m and f are asked about cellphone usage. The population being studied?

HS students in the U.S

You have data on summer earnings of a sample of 1,000 HS students. What kind of graph should you use?

Histogram

Your school has exactly 500 female and male students. Recording the gender of the first 50, what should you expect?

Most of the time, close to 25m and 25f

If your score is in the 60th percentile you know its..

between the median and 3rd quartile

The mean of the distribution is

clearly less than the median

The std dev is the measurement of...

the spread or variability of a distribution