1342 final exam review

The distribution of salaries of professional basketball players is apx sym. Which measure of central tendency would be the best measure to determine the location of the center of the distribution?

mean

The highest point on the graph of the normal density curve is located at

mean

The normal density curve is symmetric about

mean

Suppose we have a data set of the number of car accidents per day in Los Angeles during the year 2013. The data was input into a spreadsheet manually by an assistant at the Department of Transportation. For one day in July 2013, he input that there were 14 car accidents; but there were actually only 140 that day. How will this error affect the measures of center for this data?

mean will be lower due to outlier and median is not affected

In a unimodal, symmetrical distribution what are the same value?

mean=median=mode

if you have a right skewed distribution or histogram, what is the relationship between the mean, median, and the mode?

mean>median>mode

In the game of craps, two dice are tossed and the up faces are totaled. Is the event getting a total of 9 and one of the dice showing a 6 mutually exclusive?

no

can both the null and alternative be true at the same time?

no

r=.2 then what is the value of R

.04

what is the mostly used alpha?

.05

Mathematically speaking, the correlation coefficient is a measure of what? A. how far all of the data points are from a horizontal line B. how far the data points are from a vertical line C. how far all of the data points are from the line of best fit D. how far all of the data points are from zero

C. how far all of the data points are from the line of best fit

The null hypothesis is the statement of _________ and always has a ______ sign. The alternative hypothesis is the __________ hypothesis. It is a statement about the value of a __________ that we intend to test.

no change, =, research, parameter

A hypothesis test is a "two-tailed" if the alternative hypothesis contains a _______ sign.

not equal

The ______________ hypothesis contains the "=" sign.

null

The peak shopping time at a pet store is between 8-11:00 am on Saturday mornings. Management at the pet store randomly selected 85 customers last Saturday morning and decided to observe their shopping habits. They recorded the number of items that a sample of the customers purchased as well as the total time the customers spent in the store. Identify the types of variables recorded by the pet store.

number of items-discrete and total time-continuous

what will P(A)= (by definition)

number of success/total number of outcomes

At the U.S. Open Tennis Championship a statistician keeps track of every serve that a player hits during the tournament. The statistician reported that the mean serve speed of a particular player was 95 miles per hour. Suppose that the statistician indicated that the serve speed distribution was skewed to the left. What do you think the value is actually is? smaller or larger

larger

What happens to the shape of the t distribution as the sample size increases? A. It becomes positively skewed B. It becomes negatively skewed C. It becomes normally distributed D. It become rectangular

C. It becomes normally distributed

What does it mean if a z score is equal to zero? A. The score is above the average B. The score is below the average C. The score is the same as the average D. There was a mistake in the calculations

C. The score is the same as the average

This is the visual display of data from one variable. A. Correlation B. Regression C. Univariate distribution D. Bivariate distribution

C. Univariate distribution

what happens to a CI (width) as the % of confidence increase?

increases

How do you interpret a confidence interval?

we are ___% confident that the true ____ of ......... is somewhere between ____ and _____

sample mean symbol

x̅

will an outlier effect the value of "r"?

yes

What is a Type II error called

β or a false negative

population mean symbol

μ

population standard deviation symbol

σ

population variance symbol

σ²

All probability will add up to?

1

Approximately ____% of the area under the normal curve is between 1 std dev above and below the mean.

68

what is the mostly used CI level?

95

what symbol(s) will never be in your Null?

<, > , or not equal

Binomial Probability Distribution

A probability distribution showing the probability of x successes in n trials of a binomial experiment.

One way to deal with extremely skewed data is to do which of the following? A. Eliminate 10-20% of the scores from each tail of the distribution B. Ignore the skew, as it will not affect late data analysis C. Eliminate 10-20% of the scores from the skewed side of the distribution D. Collect new data that does not have a skew

A. Eliminate 10-20% of the scores from each tail of the distribution

Most people in a community use between 3,000 and 5,000 gallons of water a month, however a few people use over 15,000 gallons a month. What kind of skew would this be? A. Positive B. Negative C. Normal D. None

A. Positive

The purpose of regression is which of the following? A. Predict the scores on one variable if you know the value of the other variable B. Decide which variable causes the other variable to occur C. Determine how much variance the two variables have in common D. Determine how big the effect is between two variables

A. Predict the scores on one variable if you know the value of the other variable

In a distribution of scores, if the left half generally mirrors the right half it is considered to be what kind of distribution? A. Symmetrical B. Positive Skew C. Negative Skew D. Bimodal

A. Symmetrical

When using Null Hypothesis Significance Testing, you begin by assuming which of the following? A. The means are equal B. The means are not equal C. You make no assumptions D. The population mean is equal to zero

A. The means are equal

Which of the following correlation values indicates that there is no relationship between two variables? A. -1.00 B. 0.00 C. +1.00

B. 0.00

This is when you draw a line of best fit from data so you can use the scores on one variable to predict scores on a second variable. A. Correlation B. Regression C. Univariate distribution D. Bivariate distribution

B. Regression

Which of the following methods should NOT be used to select a random sample? A. Draw names of out of a hat B. Stop the first person you meet on a street C. Use a table of random numbers D. Use a random sampling program on a computer

B. Stop the first person you meet on a street

What is the final step in the analysis of a dataset? A. Calculate descriptive stats B. Tell a story about what the data reveals C. Calculate inferential stats D. Check for errors in the data

B. Tell a story about what the data reveals

What does it mean is a z score if less than zero? A. The score is above the average B. The score is below the average C. The score is the same as the average D. There was a mistake in the calculations

B. The score is below the average

An unusual event is an event that has a

Low probability of occurrence

The coefficient of determination tells you which of the following pieces of information? A. If two variables are related to each other or not B. Of one variable can be used to predict scores on a second variable C. If one variable causes the other variable to occur D. What percentage of the variance in the two groups in common variance

D. What percentage of the variance in the two groups in common variance

Which of the following pieces of information is shown on a boxplot? A. Mean and Median B. Interquartile range and range C. Skew and Outliers D. a, b, and c are all shown on a boxplot

D. a, b, and c are all shown on a boxplot

The ______________ probability of an outcome is obtained by dividing the frequency of occurrence of an event by the number of trials of the experiment.

Empirical

A researcher wants to know whether athletic women are more flexible than non-athletic women. For this experiment, a woman who exercised vigorously at least four times per week was considered "athletic". Flexibility is measured in inches on a sit & reach box. A researcher tested his claim using the following summary statistics: Assume that all conditions for testing have been met. t = 1.626; p = 0.057 ; At the 1% significance level, state your decision regarding the null hypothesis and your conclusion about the original claim.

Fail to reject the null hypothesis; there is not strong enough evidence to suggest that athletic women are more flexible, on average, than non-athletic women.

If A and B are independent events, then A and B are mutually exclusive also. true or false

False

Instead of saying "FTR the null" we cans say "accept the null".

False

Practical significance is the same as statistical significance. True or False

False

Type I and Type II errors are independent events.

False

Which measure of central tendency is not resistant to extreme values in a numeric data set?

Mean

Which measure of central tendency is resistant to extreme values in a numeric data set?

Median

The measure which contains the middle 50% of the distribution is referred to as what? A. Range B. Interquartile range C. Standard Deviation D. Variance

IQR

The reading level of a random sample of men and a random sample of women are measured. Researchers want know whether women typically read at a higher level than men.

Independent

what level of measure is the variable "IQ score"?

Interval

Which measure of central tendency may not exist for all numeric data sets?

Mode

Is S=1.255, what is the shape of the distribution?

Moderately Skewed Right

There are 30 chocolates in a box, all identically shaped. There are 11 filled with nuts, 10 filled with caramel, and 9 are solid chocolate. You randomly select one piece, eat it, and then select a second piece. Is this an example of independence?

NO

r=-.788, what is the direction and strength?

Negative and strong

what level of measure is the variable "Movie Ratings"?

Ordinal

This is a number that represents a population.

Parameter

what level of measure is the variable "GPA"?

Ratio

sample standard deviation symbol

S

Experiments assist the researcher in isolating the causes of the relationships that exist between two variables. True or False

True

Observational studies are not as useful as experiments to learn about the characteristics of a population.

True

What type of error is the worse one to make?

Type I

If we reject the null hypothesis when the null hypothesis is true, then we have made a

Type I error

If a distribution has outliers, but is approximately symmetrical, then the best measure of spread is?

Standard deviation

This is a number that represents a sample.

Statistic

The level of significance, α, is the probability of making a

Type I error or a false positive

What effect will an outlier have on a confidence interval that is based on a small sample size?

The confidence interval will be wider than an interval without the outlier.

If we do not reject the null hypothesis when the null hypothesis is in error, then we have made a

Type II error

A local tennis pro-shop strings tennis rackets at the tension (pounds per square inch) requested by the customer. Recently a customer made a claim that the pro-shop consistently strings rackets at lower tensions, on average, than requested. To support this claim, the customer asked the pro shop to string 10 new rackets at 41 psi. Suppose the two-tailed P-value for the test described above (obtained from a computer printout) is Give the proper conclusion for the test. Use

There is sufficient evidence to conclude that μ, the true mean tension of the rackets, is less than 41 psi.

An event is any collection of outcomes from a probability experiment.

True

Binomial Probability Formula

When n independent repeated trials occur, where p = probability of success and q = probability of failure with p and q (where q = 1 − p) remaining constant throughout all n trials, the probability of exactly x successes is calculated as follows. P (x) = nCxpxqn−x=n!x!(n−x)! pxqn−x

What situation has to be true in order for a confidence interval and a hypothesis test will yield the same results.

When the alternative hypothesis is two-tailed.

The _________of an event A is the event that A does not occur.

complement

The grade point averages for 10 randomly selected students in an algebra class with 125 students are listed below. What is the effect on the width of the confidence interval if the sample size is increased to 20? 2.0 3.2 1.8 2.9 0.9 4.0 3.3 2.9 3.6 0.8

decreases

This is when a number between scores are not meaningful, like having 1.5 siblings. A. Continuous variable B. Discrete variable C. Categorial variables

discrete

In terms of probability, a(n) ___________________ is any process with uncertain results that can be repeated.

experiment

looking at a histogram, how do you know if there are any possible outlier(s)?

gaps between bars

A ______________ is a statement or claim regarding a characteristic of one or more populations.

hypothesis

simple regression: if you have a regression equation, when is the only time you can use that to predict an outcome? when the value of "x" is?

in the predication range

what do yo have to know in order to compute a Z interval or a Z test?

population SD

Step 1 of all hypothesis testing is about the?

population parameter

A research hypothesis is always expressed in terms of ________ __________ because we are interested in making statements about the _________ based on _______ statistics.

population, parameter, population sample

what is the variable "Gender" be regarded as?

qualitative and nominal level

"age of a person" is what kind of variable? categorical or quantitative

quantitative

A subset scores from a larger group is referred to as what?

sample

A(n) _______________ of a probability experiment is the collection of all outcomes possible.

sample space

is the p-value is less then .01, then there ----- difference in the two means.

significant

what is another name for alpha?

significant level or type I error

if a histogram as a tail on the left side, then the shape of the graph is?

skewed Left

Many firms use on-the-job training to teach their employees computer programming. Suppose you work in the personnel department of a firm that just finished training a group of its employees to program, and you have been requested to review the performance of one of the trainees on the final test that was given to all trainees. The mean of the test scores is 74. Additional information indicated that the median of the test scores was 84. What type of distribution most likely describes the shape of the test scores?

skewed to the left

Classify the statement as an example of classical probability, empirical probability, or subjective probability. The probability that it will snow tomorrow is 68%.

subjective

sample variance symbol

s²

Two events, A and B, are independent if P(A and B) = P(A) ∙ P(B). true or false

true

if a histogram has "one peak" then its overall pattern will look like?

unimodal distribution