Stat Final 5/29
To estimate p, you will use the proportion p=150/250 of your sample who favored eliminating the carnival.
statistic
An opinion poll asks a sample of 1100 people whether they support reducing the number of legal immigrants to the U.S.; 53% of these 1100 people say "yes". the number 53% is a...
statistic.
The GSS begins by dividing the 3000 counties in the country up into urban, rural, and suburban; then a separate sample is chosen at random from each group. this is
stratified random sample
A study found that SAT verbal scores were positively associated with first-year grade point averages for liberal arts majors. We can conclude from this that...
students who scored high on the SAT verbal test tended to get higher GPAs than those who scored lower on SAT verbal test
Confounding often defeats attempts to show that one variable causes changes in another variable. Confounding means that
the effects of several variables are mixed up, so we cannot say which is causing the response
For a distribution that is skewed to the right, usually
the mean will be larger than the median
Which statistical measure is NOT strongly affected by a few outliers in the data?
the median
The box in the center of a box plot marks...
the range covered by the middle half of the data
Corn variety #1 yielded 140 bushels per acre last year at a research farms. This year, corn variety #2, planted in the same location, yielded only 110 bushels per acre. unfortunately, we don't know whether the difference is due to the superiority of variety #1 or to the effect of this year's drought. This is an example of
Confounding
Which of the following is least likely to have a nearly normal distribution?
Family incomes of all students taking STAT 001 at State Tech.
How many treatments did this experiment compare?
Four
I perform a test of significance and I calculate a p-value of 0.025. which of the following statements is true?
I would reject the ho at 5% level, but not have the 1% level
On the American Mathematical Contest Exam, John got his results and it said he was in the 87th percentile. Which of the following is true?
John's score was the same or better Tham 87% of all students that took the same AMC exam
The experiment was "double-blind" this means that
Neither the subjects nor the people who worked with them knew whether they were taking bupropion or placebo.
A study of 3,617 adults found that those who attend religious services live longer (on the average) than those who don't. Is this good evidence that attending services causes longer life?
No, because religious people may differ from non-religious people in other ways, such as smoking and drinking, that affects life span.
The GSS finds that 28% of the 1500 people interviewed do not approve of capital punishment. The number 28% is
a Statistics
Th subjects of the study included both men and women. If the men and women were separately assigned to treatments, using the table of random digits twice, the design would be
a block design
You work for an advertising agency that is preparing a new television commercial to appeal to women. You have been asked to design an experiment to compare the effectiveness of three versions of the commercial. each subject will be shown one of three versions and then asked her attitude toward the product. You think there may be large differences between women who are employed and those who are not. Because of these differences you should use
a block design
In an experiment to see if aspirin reduces the chance of having a heart attack, a placebo is
a dummy pill that looks like aspirin but has no active ingredients
In a randomized block design the blocks often represent levels of
a lurking variable suspected of being confounded with the explanatory variable
Suppose that 62% of all adults favor balancing the budget over cutting taxes. The number 62% is
a parameter
Were the extinctions that occurred in the last ice age more frequent among species of animals with large body sizes? A researcher gathers data on the average body mass (in kilograms) of all species known to have existed at that time. These Measurements are values of...
a quantitative variable
The population for GSS is..
all adult residents of the U.S.
The essential difference between an experiment and an observational study is
an experiment imposes treatments on the subjects, but an observational study does not.
A radio talk show invites listeners to calla telephone number to invites listeners to call a telephone number to vote "yes" or "No" on whether they support a bond issue for a new school. About 1500 people call in. Over 80% say "no" as an estimate of community opinion, this result is...
badly biased due to voluntary responses
A well-drawn histogram should have...
bars all the same width, no space between bars (unless a class has no observations), a clearly marked vertical scale
If your score on a test is at the 60th percentile, you know that your score lies
between the median and the third quartile.
Voluntary response polls almost always suffer from
big bias
You are planning an experiment to study the effect of gasoline brand and vehicle weight on the gas mileage (miles per gallon) of sport utility vehicles. In this study,
gas mileage is a response variable
Suppose that a normal model described students scores in a history class. Parker has a standardized score (z-score) of +2.5. This means that parker
is 2.5 standard deviations above average for the class
One group received a placebo. why not just give this group no treatment at all?
just thinking you are getting a treatment may have an effect, and we want to see if the real treatments do better than this.
The five-number summary of a distribution consists of...
minimum, maximum, median, q1, and q3
The mean of T is
150
What percent of students who drink 5 beers have BAC above 0.19 (the legal limit for driving other states)?
2.5%
The middle 95% of students who drink 5 beers have BAC between
0.04 and 0.12
in this situation,
0.1% is a parameter and 9 is a statistic
The probability of finding 3 people in a household is the same as the probability of finding 4 people. These probabilities are marked ??? in the table of distribution. the probability that a household contains 3 people must be
0.32
A recent Gallup poll interviewed a random sample of 1523 adults. of these, 868 bought a lottery ticket in the past year. a 95% confidence interval for the proportion of all adults who bought a lottery ticket in the past year is (assume Gallup used an SRS)
0.57 +- 0.025
IF this die is thrown and the top face shows an odd number, what is the probability that the die shows a 1?
0.60
Which correlation indicates a strong positive straight line relationship?
0.99
You must choose a simple random sample of 7 packages from a shipment of 80 packages of vaccine for testing. You label the packages 01, 02, 03,..., 80 and then use the random number table to select your sample/ The chance that any one package is chosen for the sample.
1 in 80
You will take a simple random sample of 3 cases from a population of 11 cases of wine, which are marked a,b,c,d,e,f,g,h,i,j,k. you assign numbers as labels to the cases ignorer to use the random digit table. Which of the following is an incorrect assignment?
1,2,3,4,5,6,7,8,9,10,11 0,1,2,3,4,5,6,7,8,9,10
The equation of the regression line tells us that (on the average) when the male illiteracy rate goes up by 1%, the female rate goes up by...
1.39%
A correlation cannot have the value..
1.5
SAT scores are normally distributed with mean 500 and standard deviation 100. Julie scores 650. Her standard score is
1.5
a 95% confidence interval for the population proportion p is
1.67 +- 0.03
Whats the expected number of cars in a randomly selected American household?
1.75
The standard deviations of T is
11.66
Here is a set of data: 1300,18,25,19,-7,24. Which observation is the outlier?
1300 and -7
The standard deviation of the returns is...
14.74
In China, 10.1% of men are illiterate. Predict the percent of illiterate women in China.
17.4%
For a normal distribution with mean 20 and standard deviation 5, approximately what percent of the observations will be less than 10?
2.5%
a housing company build houses with two-car garages. What percent of households have more cars than the garage can hold?
20%
The mean return is...
20.07
The media return during this period is...
25.8
If the least squares regression line for predicting y from x is y=500-20x, what is the predicted value of y when x=10?
300
The third quartile of these returns is...
31.7
The distribution of heights of adult men is approximately normal. A man is at the 61.79th percentile. what percent of all men are taller than he is?
38.21%
Based on the sample data, the producer estimates that the promotion of contaminated eggs in the population is about...
4.5%
For a normal distribution with mean 20 and standard deviation 5, approximately what percent of the observations will be less than 20?
50%
What percent of students who drink 5 beers have BAC above 0.08 (the legal limit for driving in most states)?
50%
The most common bet in craps is the "pass line" a pass line bettor wins immediately neither a 7 or an 11 comes up on the first roll. this is called a natural. what is the probability of a natural?
8/36
For a normal distribution with mean 20 and standard deviations 5, approxiametly what percent of the observations will be between 5 and 35?
99.7%
the subjects of the study included both men and women. All of the subjects were randomly assigned among all the treatments with on use of the table of random digits. This design is called
A completely randomized design
A simple random sample is
A sample that gives every possible sample of the same size the same chance to be selected.
Professor Gans has obtained
A stratified random sample, where the strata are students with different zodiac signs.
The figure above is the density curve of a distribution. This distribution is
Skewed to the left
The United Presbyterian Church recently took a sample of opinion in the church. The overall sample "contains independent random samples of 1537 members, 1400 elders, 1513 pastors and 714 other clergy." This sampling design is a...
Stratified sample.
A quality control inspector on an assembly line making microwave ovens randomly chooses one of the first ten ovens manufactured each day. This oven and every tenth oven thereafter gets inspected. This is called
Systematic random sampling
An example of categorical variable is...
The name of the college a student attends and a student's sex (Male or Female)
The drug manufacturers Merck recently stopped testing a promising new drug to treat depression. It turned out that in a randomized, double-blind trial a dummy pill did almost as well as the new drug. The fact that many people respond to a dummy treatment is called
The placebo effect
The ___ you want to estimate is the proportion (p) of all undergraduates who favor eliminated the carnival.
parameter
Which of these is NOT true of the correlation r between the lengths in inches and weights in pounds of a sample of brook trout?
r is measured in inches
Increasing the sample size of an opinion poll will
reduce the variability of the poll result
A a90% confidence interval based on this same sample would have
the same center and a smaller margin of error
The standard deviation is a measure of...
the spread of a distribution
The correlation between two variables is of -0.8. we can conclude..
there is a strong negative association between the two variables
A member of congress receives 1128 letters about proposed legislation that would provide government insurance for nursing-home care. Over 80% oppose the legislation this a sample can't be trusted because
there is bias due to voluntary response
China has 1.2 billion people. marketers want to know which international brands that have heard of. a large study showed that 62% of all Chinese adults have heard of coca-cola. you want to simulate choosing a Chinese at random and asking if he or she has heard of coca-cola. one correct way to assign random digits to simulate the answer is:
two digits simulate one person's answer; 00 and 61 mean "yes" and 62-99 mean "no"
the phrase "95% confidence" means that
unrepeated campings, our interval will contain the true parameter 95% of the time
The null hypothesis is
usually a claim about the population
If a significance test gives a p-value of 0.25
we would fail to reject the HO when alpha is 0.05
The response variable in this experiment is
whether or not a subject was able to abstain from smoking for a year.
