STAT 145

Null and alternative hypothesizes are statements about a. population parameters b. sample parameters c. sample statistics d. it depends sometimes population parameters and sometimes sample statistics

a. population parameters

The collection of all elements of interest in a particular study is a. the population b. the sampling c. statistical inference d. descriptive statistics

a. the population

The sum of deviations of the individual data elements from their mean is _______________

always equal to zero

The coefficient of correlation ranges between a. 0 and 1 b. -1 and +1 c. minus infinity and plus infinity d. 1 and 100

b. -1 and +1

What is the variance?

(standard deviation)^2

Which of the following displays can be used to describe two quantitative variables? A) scatterplot B) contingency table C) side-by-side bar graph D) histogram E) all of these

scatterplot

A histogram is skewed to the ____________

side that is skied down

regression coefficient

slope

One characteristic of a bar chart is: A) It is used for categorical data. B) the bars can be displayed either vertically or horizontally. C) it is used to display the distribution of a continuous variable. D) It can show either frequency or relative frequency.

the bars can be displayed either vertically or horizontally.

When a higher confidence level is used to estimate a proportion and all other factors involved are held constant a. the confidence interval will be narrower. b. the confidence interval will not be affected. c. the confidence interval will be wider. d. the confidence interval will be less likely to contain the parameter being estimated. e. there is not enough information to determine the effect on the confidence interval.

the confidence interval will be wider.

A result is called statistically significant when ______________

the p value is less or equal to the significance level

In developing a confidence interval estimate for the population mean, the t-distribution is used to obtain the critical value when: A) the sample contains extreme values. B) the population standard deviation is unknown. C) np(1-p)>10. D) n < 30.

the population standard deviation is unknown.

When n > 30, the Central Limit Theorem tells us that a. the population is normally distributed b. the sampling distribution is normally distributed c. the sample is normally distributed d. we need a larger sample

the sampling distribution is normally distributed

Which of the following is not a measure of central location? a. mean b. median c. variance d. mode

variance

In hypothesis testing if the null hypothesis is rejected

we conclude the alternative hypothesis is true

x vs x bar

x bar has a sample size

proportion table

z table

2 standard deviations

95%

3 standard deviations

99%

When should the decision of a test be to accept Ho?

Never

1 standard deviation

68%

CI table

1 page t table

Which of the following is a characteristic of the normal probability distribution? 1. The mean, median, and the mode are equal 2. The distribution is not symmetrical 3. The standard deviation must be 0 4. The standard deviation must be 1

1. The mean, median, and the mode are equal

In a standard normal distribution, the 1. mean and the standard deviation are both 1 2. mean is 0 and the standard deviation is 1 3. mean is 1 and the standard deviation is 0 4. mean and the standard deviation can have any value

2. mean is 0 and the standard deviation is 1

mean and mu table

3 page t table

Which of the following has the potential for affecting the relationship between the response and explanatory variable, but was not measured by the study? A) A lurking variable B) A missing variable C) Outliers D) None of these E) All of these

A lurking variable

Which of the following statements is true with respect to the t-distribution? A) The t-distribution is symmetrical. B) The exact shape of the t-distribution depends on the number of degrees of freedom. C) The t-distribution is more spread out than the standard normal distribution. D) All of the above are true.

All of the above are true.

The error of rejecting a true null hypothesis is A) a Type I error B) a Type II error C) is the same as α D) committed when not enough information is available

B) a Type II error

A Type II error is committed when A) a true alternative hypothesis is mistakenly rejected B) a true null hypothesis is mistakenly rejected C) the sample size has been too small D) not enough information has been available

B) a true null hypothesis is mistakenly rejected

What is used in the 5 number summary?

Min Q1 Median Q3 Max (which can be an outlier)

If the correlation is approximately zero, then one can conclude A) that there is no relationship between x and y. B) that there is no linear relationship between x and y. C) that there is a linear relationship between x and y. D) depends on the units of measurement of x. E) None of these.

B) that there is no linear relationship between x and y.

Which of the following is not true with regards to a p value? A. a p value is a probability and must be between 0 and 1 B. a p value does not tell us the probability that the null hypothesis is true C. the larger the p value, the more conclusive the evidence is against the null hypothesis D. a p value indicates the strength of the evidence against the null hypothesis

C. the larger the p value, the more conclusive the evidence is against the null hypothesis

Summarizing the data that are obtained refers to which aspect of statistics? A) Description B) Hypothesis C) Inference D) Probability E) None of these

Description

Which of the following is not a characteristic of the normal distribution? A) Symmetric B) Mean = median = mode C) Bell-shaped D) Equal probabilities at all values of x

Equal probabilities at all values of x

Making decisions and predictions based on the data refers to which aspect of statistics? A) Graphical Analysis B) Description C) Inference D) Sampling E) None of these

Inference

Stating that 90% of the taste testers preferred the new brand is an example of which type of statistics? A) Description B) Design C) Inference D) Investigation E) None of these

Inference

Which of the following is NOT true of a bar chart? A) The bars can be either horizontal or vertical. B) It is used for numerical data. C) It can show either frequency or relative frequency. D) It is used for categorical data.

It is used for numerical data.

Lower fence

Q1 - 1.5(IQR)

Upper fence

Q3 + 1.5(IQR)

Which of the following measures is not affected by extreme values in the data? A) The mean B) The median C) The range D) The mode E) The standard deviation

The median

Writing conclusion Hypothesis tests

The true mean/proportion of _____________ is/isnt significantly ________________________

Writing conclusion for confidence intervals

We can be 95% confidence that (parameter) is between _________ and __________

IQR

Where middle 50% of data lies Q3-Q1

μ is an example of a a. population parameter b. sample statistic c. population variance d. mode

a. population parameter

One of the key differences between a bar chart and histogram is: A) the histogram contains gaps between the bars and the bar chart does not. B) a bar chart is used to display a categorical variable and a histogram is used to display the distribution of a quantitative variable. C) the histogram shows relative frequency while the bar chart shows frequency. D) the bar chart must be vertical while the histogram must be horizontal.

a bar chart is used to display a categorical variable and a histogram is used to display the distribution of a quantitative variable.

A numerical summary of the population is called A) a census B) a parameter C) a data file D) a statistic E) a variable

a parameter

A summary measure that is computed from a sample to describe a characteristic of interest is called A) a poll B) a data file C) a statistic D) a parameter E) a variable

a statistic

Arithmetic operations are inappropriate for a. categorical data b. quantitative data c. both categorical and quantitative data d. large data sets

a. categorical data

The ability of an interval estimate to contain the value of the population parameter is described by the a. confidence level b. degrees of freedom c. precise value of the population mean d. degrees of freedom minus 1

a. confidence level

The sampling distribution of the sample means a. is the probability distribution showing all possible values of the sample mean b. is used as a point estimator of the population mean is an unbiased estimator c. is an unbiased estimator d. shows the distribution of all possible values of μ

a. is the probability distribution showing all possible values of the sample mean

As the number of degrees of freedom for a t distribution increases, the difference between the t distributionand the standard normal distribution a. becomes larger b. becomes smaller c. stays the same d. None of these alternatives is correct.

b. becomes smaller

In point estimation a. data from the population is used to estimate the population parameter b. data from the sample is used to estimate the population parameter c. data from the sample is used to estimate the sample statistic d. the mean of the population equals the mean of the sample

b. data from the sample is used to estimate the population parameter

The summaries of data, which may be tabular, graphical, or numerical, are referred to as a. inferential statistics b. descriptive statistics c. statistical inference d. report generation

b. descriptive statistics

Statistical inference a. is the process of drawing inferences about the sample b. is the process of drawing inferences about the population based on the information taken from the sample c. is the organization and summarization of collected information. d. Is collecting, analyzing and summarizing data

b. is the process of drawing inferences about the population based on the information taken from the sample

The level of significance is the a. maximum allowable probability of Type II error b. maximum allowable probability of Type I error c. same as the confidence coefficient d. same as the p-value

b. maximum allowable probability of Type I error

The z score and percentiles are measures of a. location b. relative location c. variability d. relative frequency

b. relative location

What is the distribution o the values of a statistic called? a. normal distribution b. sampling distribution c. probability model d. central limit theorem

b. sampling distribution

The probability distribution of the sample mean is called the a. central probability distribution b. sampling distribution of the mean c. random variation d. standard error

b. sampling distribution of the mean

The degree of risk you are willing to take that you will reject a null hypothesis when it is actually true is the a. confidence level b. significance level c. margin of error d. p-value

b. significance level

Which of the following is the most sensitive to outliers? a. interquartile range b. standard deviation c. median d. mode

b. standard deviation

The process of analyzing sample data in order to draw conclusions about the characteristics of a population is called a. descriptive statistics b. statistical inference c. data analysis d. data summarization

b. statistical inference

When "S" is used to estimate "σ," the margin of error is computed by using a. normal distribution b. t distribution c. the mean of the sample d. the mean of the population

b. t distribution

Which of the following is not a measure of dispersion? a. the range b. the 50th percentile c. the standard deviation d. the interquartile range

b. the 50th percentile

Which of the following is a fraction of a sample that has a certain trait or characteristic? a. the mean b. the sample proportion c. the population proportion d. the coefficient of variation

b. the sample proportion

The mean of a random variable describes a.the number of trials in a binomial experiment b. the variability of the variable's probability distribution. c. the location of the variable's probability distribution d.the extent of the spread of the variable's probability distribution.

b. the variability of the variable's probability distribution.

In interval estimation, as the sample size becomes larger, the interval estimate a. becomes narrower b. becomes wider c. remains the same, since the mean d. is not changing gets closer to 1.96

becomes narrorer

The median of a sample will always equal the a. mode b. mean c. 50th percentile d. all of the above answers are correct

c. 50th percentile

Quantitative data a. are always nonnumeric b. may be either numeric or nonnumeric c. are always numeric d. None of these alternatives is correct.

c. are always numeric

Data a. are always be numeric b. are always nonnumeric c. are the raw material of statistics d. None of these alternatives is correct.

c. are the raw material of statistics

The median is a measure of a. relative dispersion b. absolute dispersion c. central location d. relative location

c. central location

A numerical measure of linear association between two variables is the a. variance b. coefficient of variation c. correlation coefficient d. standard deviation

c. correlation coefficient

Statistical inference a. refers to the process of drawing inferences about the sample based on the characteristics of the population b. is the same as descriptive statistics c. is the process of drawing inferences about the population based on the information taken from the sample d. is the same as a census

c. is the process of drawing inferences about the population based on the information taken from the sample

A numerical value used as a summary measure for a sample, such as sample mean, is known as a a. population parameter b. sample parameter c. sample statistic d. population mean

c. sample statistic

A population is a. the same as a sample b. the selection of a random sample c. the collection of all items of interest in a particular study d. always the same size as the sample

c. the collection of all items of interest in a particular study

The measure of dispersion that is influenced most by extreme values is a. the variance b. the standard deviation c. the range d. the interquartile range

c. the range

Gender is an example of a ______________ variable

categorical

Social security numbers consist of numeric values. Therefore, social security is an example of a. a quantitative variable b. either a quantitative or a categorical variable c. an exchange variable d. a categorical variable

d. a categorical variable

A portion of the population selected to represent the population is called a. statistical inference b. descriptive statistics c. a census d. a sample

d. a sample

Which of the following is a measure of dispersion? a. percentiles b. quartiles c. interquartile range d. all of the above are measures of dispersion

d. all of the above are measures of dispersion

Categorical data a. must be numeric b. must be nonnumeric c. cannot be numeric d. may be either numeric or nonnumeric

d. may be either numeric or nonnumeric

The p value a. can be any value b. can be any positive value c. can be any value, negative or positive d. must be a value between 0 and 1

d. must be a value between 0 and 1

In hypothesis testing if the null hypothesis has been rejected when the alternative hypothesis has been true a. a Type I error has been committed b. a Type II error has been committed c. either a Type I or Type II error has been committed d. the correct decision has been made

d. the correct decision has been made

The interquartile range is a. the 50th percentile b. another name for the variance c. the difference between the largest and smallest values d. the difference between the third quartile and the first quartile

d. the difference between the third quartile and the first quartile

The descriptive measure of dispersion that is based on the concept of a deviation about the mean is a. the range b. the interquartile range c. the absolute value of the range d. the standard deviation

d. the standard deviation

The value of the sum of the deviations from the mean, i.e., must always be a. less than the zero b. negative c. either positive or negative depending on whether the mean is negative or positive d. zero

d. zero

As the sample size increases, the margin of error a. increases b. decreases c. stays the same d. increases or decreases depending on the size of the mean

decreases

A stem and leaf diagram is used to: A) display the distribution of a quantitative variable. B) show the joint relationship between two variables. C) graph a joint frequency distribution. D) show relative cumulative frequency.

display the distribution of a quantitative variable

p value > significance level a = 0.05

do not reject Ho cannot conclude Ha is not significantly _______

Type II error

don't reject the null hypothesis when you should have

The most common graphical presentation of quantitative data is a a. histogram b. bar chart c. relative frequency d. pie chart

histogram

If a decision maker wishes to reduce the margin of error associated with a confidence interval estimate for a population mean, she can: A) decrease the sample size. C) increase the sample size. B) increase the confidence level. D) use the t-distribution.

increase the sample size.

When a pair of dice are rolled, the outcome for each die can be said to be: A) mutually exclusive. B) mutually inclusive. C) dependent. D) independent.

independent

The normal distribution is symmetric about its ___________

mean

Which of the following provides a measure of central location for the data? a. standard deviation b. mean c. variance d. range

mean

What do you do with the p-value in a two tailed test?

multiply by 2

The numerical value of the standard deviation can never be a. larger than the variance b. zero c. negative d. smaller than the variance

negative

satisfying assumptions

np(1 - p) > 10 n>30 by CLT X approx normal then x bar approx normal

correlation coeffiecient

r

Which of the following is not a property of r? A) r does not depend on which variable is treated as the response variable. B) r measures the strength of any kind of relationship between x and y. C) r does not depend on the units of y or x. D) r is always between -1 and 1. E) The closer r is to zero, the weaker the linear relationship between x and y.

r measures the strength of any kind of relationship between x and y.

coefficient of determination

r^2 % of variation of y that is explained in x

The difference between the largest and the smallest data values is the a. variance b. interquartile range c. range d. coefficient of variation

range

p value < significance level a = 0.05

reject Ho can conclude Ha parameter IS significantly ______________

Type 1 error

rejecting null hypothesis when you're not supposed tp