Tessa Final Reading quizzes
The complement of an event A is _________________.
1.)the set of outcomes that are not in the event 2.)of probability 1 minus the probability that the event A occurs 3.)denoted A to the power of c
Trials are Bernoulli if ____________, ____________, and _____________ .
1.)the trials are independent 2.) only two possible outcomes 3.) the probability of success is the same on every tria
We usually nominate a point as an outlier if it lies farther than ______________ beyond either the lower quartile (Q1) or upper quartile (Q3). (Refer to Page 55 on the textbook)
1.5 IQRs
A student wants to determine whether or not a value in her data is an outlier. She has calculated Q1 = 4, median = 5, and Q3 = 10. Where is the upper fence?
19
For a boxplot, the box itself represents ______________ percent of the observations
50
The interquartile range (IQR) summarizes the spread by focusing on the middle ____________ % of the data.
50
he value of 7!
5040
Which of the following is not a difference between bar charts and histograms?
A bar chart is used for quantitative variables while a histogram is used for categorical variables.
Tessa has kept records on grades that students have earned in her class. If she wants to examine the percentage of students earning the grades A, B, C, D, and F during the most recent term, which kind of plot could she make?
A. Pie chart
In the following examples, which one is NOT from a random selection?
Asking your friend to give a number from 1 to 10
You are writing an article for the college newspaper about the cost of attending college. You want to make a graph to compare costs at your school and three similar schools. A good choice of a graph would be a ___________.
Bar Chart
A Binomial random variable can be studied as the number of successes in a series of __________ trials. Choose the correct answer below.
Bernoulli
Suppose the probability of a dropped call is 0.02. If we want to determine the probability that 2 out of the next 20 calls placed on a cell will drop, what probability model should we use?
Binomial
Which type of probability does this statement infer to: What is the probability that a temperature sensor fails given that a flow sensor has failed?
Conditional
Which of the following gives the best visual of how a whole group is partitioned into several categories? Choose the correct answer below.
D. Pie chart
Which of the following always displays percentages rather than counts? Select the correct answer below. (only one answer!)
D. Relative frequency table
: Standardizing the variables will make the correlation 0.
False
Correlation is affected by changes in the center or scale of either variable.
False
Weak associations result in a small amount of scatter in the scatterplot.
False
When we analyze data with outliers, we can simply exclude outliers.
False
You can add probabilities of events even if the events are not disjoint.
False
"Choose the linear model that passes through the most data points on the scatterplot."
False. The line usually touches none of the points. Minimize the sum of the squared errors.
A student in an intro stats course collects data at her university. She wants to model the relationship between student jobs and GPA. She collects a random sample of students and asks each for their GPA and the number of hours per week they work. She checks the conditions and makes a linear model. If GPA is the response variable, what units will the slope of her line be?
GPA points/hr
When examining the shape of a distribution of numerical data, which of the following is NOT one of the three basic characteristics of a distribution's shape? Choose the correct answer below.
How many numbers are in the data set.
A standardized value measures which of the following? Choose the correct answer below.
How many standard deviations away an observation is from the mean.
What is it about chance outcomes being random that makes random selection seem fair? I. Nobody can guess the outcome before it happens. II. When we want things to be fair, usually some underlying set of outcomes will be equally likely. III. Random outcomes display personal stakes in a particular outcome.
I and II
Which of the following is true about the standard deviation of the residuals?
It measures how much the points spread around the regression line
When a distribution contains outliers, which of the following is the best choice for a measure of center?
Median
What can we conclude from the fact that the number of liquor stores in a neighborhood is positively correlated with the crime rate in that neighborhood? Choose the correct answer below.
Neighborhoods with higher-than-average number of liquor stores typically (but not always) have a higher-than-average crime rate.
An online investment blogger advises investing in mutual funds that have performed badly the past year because "regression to the mean tells us that they will do well next year". Is he correct?
No, he is incorrect. Although the performance of funds will cluster around the mean on average, he cannot predict how any particular fund will do.
Which of the following conditions does NOT need to be checked when using correlation? Choose the correct answer below.
Normal Condition
Indicate if the following represents independent event. Prices of houses on the same block. Choose the correct answer below.
Not independent, because the outcome of one trial does influence or change the outcome of another.
A CEO complains that the winners of his "rookie junior executive of the year" award often turn out to have less impressive performance the following year. He wonders whether the award actually encourages them to slack off. Which of the following is a better explanation for why the winners of the "rookie junior executive of the year" award often turn out to have less impressive performance the following year?
Perhaps they weren't really better than other rookie executives, but just happened to have a lucky year.
"Relative frequency" is the same as which of the following?
Proportion
Which of the following ways are commonly used to summarize or visualize a categorical variable? ? Choose the correct "answers" below.
Relative frequency table Bar chart Pie chart
A nutritional consulting company is trying to find what percentage of the population of a town is overweight. The marketing department of the company contacts by telephone 600 people from a list of the entire town's population. All 100 people give answers to the survey. Which of the following is the most significant source of bias in this survey? Choose the correct answer below.
Response bias.
A random sample of records of home sales from Feb. 15 to Apr. 30, 1993, from the files maintained by a board of realtors gives the Price and Size (in square feet) of 117 homes. A regression model to predict Price (in thousands of dollars) from Size was constructed. What units does the slope have? Hint: You should figure out the the response variable first.
The slope has units of thousands of dollars per square foot.
The correlation coefficient is used to determine: _______________ .
The strength of the linear association between the x and y variables
Even though commercial airlines have excellent safety records, in the weeks following a crash, airlines often report a drop in the number of passengers, probably because people are afraid to risk flying. A travel agent suggests that since the Law of Averages makes it highly unlikely to have two plane crashes within a few weeks of each other, flying soon after a crash is the safest time. What do you think?
There is no such thing as the "Law of Averages." The overall probability of an airplane crash does not change due to recent crashes.
Because the Normal distribution is symmetric, the mean is in the exact center of the distributi
True
Disjoint events have no outcomes in common.
True
True or False: The standard Normal model is an important concept, because it allows us to find probabilities for any Normal model.
True
A stem-and-leaf plot is often useful in which of the following cases?
When technology is not available and the data set is not large.
Which of the following situations is an example of CAUSATION? Choose the correct answer below.
Which of the following situations is an example of CAUSATION? Choose the correct answer below.
Can we use probability models based on Bernoulli trials to investigate the following situation? A manufacturer recalls a doll because about 5% have buttons that are not properly attached. Customers return 45 of these dolls. Is the manufacturer likely to find any dangerous buttons?
Yes, because these trials may be considered Bernoulli trials since the sample is less than 10% of the population
A company that relies on Internet-based advertising linked to key search terms wants to understand the relationship between the amount it spends on this advertising and revenue (in $). In the above case, [1] is the explanatory variable and [2] is the response variable.
[1] = advertising expenditure; [2] = revenue.
The Multiplication Rule requires the events to be [1] for finding the probability that two events occur at the same time. The Addition Rule allows us to add the probabilities of [2] events to get the probability that either event occurs. Choose the correct answer below regarding [1] and [2].
[1] = independent; [2] = disjoint
Interviewing all members of a given population is called _____________. Choose the correct answer below.
a census
A survey will be given to 100 students randomly selected from the freshmen class at Lincoln High School. What is the population?
all freshmen at Lincoln High School
A probability model (distribution) tells us ___________ and ___________. Choose the correct answers below. (Pick two)
all the possible outcomes of a random experiment and the probability of each outcome
In a histogram, observations are grouped into intervals called _____________ .
bins
The plot we use to display the information from a five-number summary is called a ____________.
boxplot
If a researcher selected five schools at random and then interviewed each of the teachers in those five schools, the researcher used _________________. Choose the correct answer below.
cluster random sampling
Which of the following is an example of a random sampling method?
cluster random sampling
Boxplots are probably most useful for _________________. Choose the correct answer below.
comparing several distributions side by side
The P(B|A) is most accurately defined as the ____________________.
conditional probability that event B will occur given the event A occurs
Which of the following is an example of a nonrandom sampling method?
convenience sampling
When studying scatterplots, we should look for __________, ___________, and ____________
direction form strength
The probability we get based on repeatedly observing the event's outcome is often called ______________.
empirical probability
: When comparing two groups, use different scales, if necessary, for clarity and sizing.
false
Random events are always equally likely.
false
True / False: When we shift the data by adding a positive constant to each value, all measures of position (center, percentiles, min, max) will decrease by the same constant.
false
True or False: Disjoint events can be independent.
false
indicate if the following represents independent events. The last digit of social security numbers of students in a class.
independent, because the outcome of one trial doesn't influence or change the outcome of another.
A website reports that 48% of their users are from outside the United States and that 41% of their users log on to their website every day. Suppose that 12% of their users are United States users who log on every day. What type of probability is the 12% mentioned above?
joint probability
A hidden variable that stands behind a relationship and determines it by simultaneously affecting the other two variables is called a ____________ variable. Choose the correct answer below.
lurking
A fitted least squares regression line ___________________.
may be used to predict a value of y if the corresponding x value is given
For a boxplot, the horizontal line inside the box (or vertical line) indicates the location of the_____________.
median
The value that would be right in the middle if you were to sort the data from smallest to largest is called the
median
What are the five numbers (measurements) we use when we report the five-number summary of a distribution? Choose the correct answer below.
min, Q1, median, Q3, max
Values so large or so small that they do not fit into the pattern of the distribution are called what?
outliers
You are doing a study for a non-profit group helping at-risk children in your city. Suppose you know that 14.2% of the children in your city live in poverty. This percentage is an example of a __________.
parameter
We use a histogram to display ________________ data
quantitative
The best sample is one that is _______________.
representative of the population
A mean is known as a statistic if it is computed from the _____________.
sample
Fifty bottles of water were randomly selected from a large collection of bottles in a company's warehouse. These fifty bottles are referred to as the _____________. Choose the correct answer below.
sample
We call the collection of all possible outcomes a _____________.
sample space
When every member of the accessible population has an equal chance of being selected to participate in the study, the researcher is using ________________. Choose the correct answer below.
simple random sampling
The ___________ is a number that measures how far away the typical observation is from the mean.
standard deviation
Administrators at a university were interested in estimating the percentage of students who are the first in their family to go to college. The university student body has about 41,000 members. The administrators use a computer-based list of registered students, contact 100 freshmen, 100 sophomores, 100 juniors, and 100 seniors selected at random from each class. Identify the sampling method above.
stratified sampling
Educational researchers ultimately want the answer to a research question to pertain to the __________________. Choose the correct answer below.
target population
Residuals are ___________________. Choose the correct answer below.
the difference between the observed response and the values predicted by the model
You have carried out a regression analysis; but, after thinking about the relationship between variables, you have decided you must swap the explanatory and the response variables. After refitting the regression model to the data you expect that ____________________.
the linear model will change
The least squares line is the line for which ______________________________ is smallest. Choose the correct answer below.
the sum of the squared residuals
: The slope of a least squared line tells us how different the mean y-value is for observations that are 1 unit apart on the x-variable.
true
Continuous outcomes (or continuous variables) cannot be listed or counted because they occur over a range.
true
Discrete outcomes (or discrete variables) are numerical values that you can list or count.
true
The intercept of a least squared line tells us the average predicted y-value for all observations that have a zero x-value.
true
Normal models are appropriate for distributions whose shapes are _________ and ___________,
unimodal roughly symmetric
When preparing a chart we must follow the area principle because ______________________.
we want to avoid misrepresentation and distortion.
In the normal curve, if the standard deviation is large, then the Normal curve is _________________.
wide and low
A student in an intro stats course calculates the upper fence in a box plot to be 15.2. Her maximum value is 17. Does she have an outlier in her dataset? Choose the correct answer below.
yes
Which of the following can be used to compare values measured in different units, such as inches and pounds?
z-score
If an observation has a z-score of 0, this means which of the following
The observation is equal to the mean.
Which of the following is not necessarily an outlier? Choose the correct answer below.
The maximum value in a dataset.
In a right-skewed distribution, which of the following is true? (Refer to Page 58 Mean or Median? on the textbook).
The mean tends to be greater than the median.
What problems do you see with asking the following question of students? "Are you the first member of your family to seek higher education?"
Several terms are poorly defined. The survey needs to specify the meaning of "family" for this purpose and the meaning of "higher education." The term "seek" is also poorly defined as it does not specify what qualifies as seeking more education.
In the following sentences, which one is NOT true?
Standardizing into z-scores change the center by making the median 0.
Two members of the PTA committee have proposed the accompanying questions to ask in seeking parent's opinions. Question 1 is "Should elementary school-age children have to pass high-stakes tests in order to remain with their classmates?" and Question 2 is "Should schools and students be held accountable for meeting yearly learning goals by testing students before they advance to the next grade?" Do you think responses to these two questions might differ? How? What kind of bias is this? Choose the correct answer below.
The answers for these two questions will definitely differ. Question 1 will probably get many "No" answers, while Question 2 will get many "Yes" answers. This is an example of response bias.
In least squares regression, which of the following is NOT a required assumption / condition about residuals?
The expected value of the residuals is one.
