Statistics Missed problems

If you could choose four numbers from 1, 2, 3, 4 and repeated numbers were allowed (such as 1, 1, 3, 2), which set of four numbers would give you the largest standard deviation? (No calculations needed.)

1,1,4,4

A longer box in the boxplot means more variability in the data.

True

If the median is closer to Q1 than it is to Q3 then the data is skewed right.

True

The median is not affected by outliers

True

Suppose 75% of students have an Ipad, you tae a random sample of 2 students, so what is the chance that neither of them own an ipad?

P(No IPad)=.25, to find the chance that both students don't have an IPad, multiply the marginal times itself. P(No Ipad and No Ipad) = .0625

The number .2 in the table for Bob represents what?

P(forgot something important and short trip), even without data, anything in a block inside the table is an And probability

Extrapolation is what?

Plugging in x values outside of the range of data

A five number summary contains the min, max, Q1, Q3, and what other value?

Q2/the 50th percentile/median

Suppose 35% of the women in a poll of Americans support candidate A for president (and 65% do not.) These results make up what kind of distribution?

conditional distribution of support given women

A listing of all possible values in a data set and how often they occurred is called a data _____________________.

distribution

A flat histogram (with a line straight across) contains no variability whatsoever, according to our definition.

false

If there are a few very small values in a data set compared to the rest of the data, the mean will be larger than the median

false

In a boxplot you can tell the exact pattern of the data set (beyond just whether the data is skewed or symmetric.)

false

Suppose the correlation between two variables X and Y is .8. That means the correlation between Y and X is -.8.

false

A __________ distribution summarizes the information from one variable ONLY, without considering ANY information from another variable.

marginal

What should the residual plot look like if the regression line fits the data well?

points fall around the horizontal line y=0, random patterns, and no fan shapes

What summary measures can be directly calculated from a boxplot?

sample size, mean, standard deviation

As we heard in lecture, the "average distance from the mean" is measured by the __________________________.

standard deviation

The five-number summary of a single data set of 100 numbers would be which of the following?

the 5 numbers that are marked off on a boxplot

From the data, Bob went on a long trip, what is the chance that he forgot to pack something important? (Forgot, didn't, short trip, long trip, P(S and F)=.2, P(S and D)=.05, P(L and F)=.6, P(L and D)=.15)

to find this, you need to divide the and probability of forgetting something on a long trip, by the total percentage of being on a long trip, so .6/.8=.75

What question can be answered using a two-way table?

whether one variable is related to a condition

Boxplot A and Boxplot B are drawn on the same axes. The box part of Boxplot A is shorter in length than the box part of Boxplot B. What can you tell about the two data sets?

you can't tell

True or False; whether or not Bob forgot something important is independent of length of his trip

this is true because while the data looks different, they actually have the same percentages if you divide by the total, so he has an equal chance of forgetting something no matter the length of the trip, which makes this independent

Which coefficients go where in a best fitting line equation?

the constant coefficient goes before the x, the other variable coefficient is what you add to equal y. (ex. Coef constant is -8.290, and the other is 3.1460, y=-8.290+3.1260)

What statistic will be the least affected by adding the outlier to the data set?

the maximum

If a data set is skewed to the left, how will the mean and median compare?

the mean will be less than the median

Which is best if you want to compare several data sets regarding shape, center, and variability?

Boxplot

Correlation measures the strength and direction of any relationship between X and Y.

False

Suppose 40% of the new employees at your company are males and 60% of the "old employees" are males. Are gender and type of employee (new/old) independent?

No

Y = 2X + 3. If you increase X by 5 what happens to Y?

Increase by 10

The personnel department keeps records on all employees in a company. Here is the information they keep in one of their data files- Employee identification number, Last name, First name, Middle initial, Department, Number of years with the company, Salary ($), Education Level (high school, some college, or college degree), Age (years) Which of the following combinations of variables would be appropriate to examine with a scatterplot?

age and salary

If a residual is negative, then that data point lies _________________ the regression line.

below

An experiment gives 3 different dosage levels of a drug to 3 groups of people. The first dosage level is a fake pill (or placebo) for comparison. We measure the blood pressure of the participants before and after the study and write down the amount by which blood pressure changed. What is the response variable?

blood pressure change