QBA Test 2

Which of the following design guidelines if followed enables the user to update the model parameters without the risk of mistakenly creating an error in a formula?

Separating the parameters from the spreadsheet model

A __________ is used to visualize sample data graphically and to draw preliminary conclusions about the possible relationship between the variables.

Scatter chart

Prediction of the mean value of the dependent variable y for values of the independent variables x1, x2, etc. that are outside the experimental range is called

extrapolation

An observation classified as part of a group with a characteristic when it actually does not hae the characteristic is termed as a(n)

false positive

Two approaches to drawing a conclusion in a hypothesis test are

p-value and critical value.

The scatter chart displays the residuals versus the dependent variable t. Which of the following conclusions can be drawn based upon this scatter chart?

residuals are not independent

The random numbers generated using Excel's RAND function follows a _______ probability distribution between 0 and 1.

uniform

Trend refers to

the long-run shift or movement in the time series observable over several periods of time

A positive forecast error indicates that the forecasting method ________ the dependent variable.

Underestimated

The finite correction factor should be used in the computation of the standard deviation of the sample mean and the standard population when n / N is

greater than 0.05.

The conceptual model

helps in organizing the data requirements

The percent of misclassified records out of the total records in the validation data is known as the

overall error rate

The CEO of a company wants to estimate the percent of employees that use company computers to go on Facebook during work hours with 95% confidence. He selects a random sample of 150 of the employees and finds that 53 of them logged onto Facebook that day. What is the point estimate of the proportion of the population that logged onto Facebook that day?

0.35

A statistics teacher started class one day by drawing the names of 10 students out of a hat and asked them to do as many pushups as they could. The 10 randomly selected students averaged 15 pushups per person with a standard deviation of 9 pushups. Suppose the distribution of the population of number of pushups that can be done is approximately normal. What is the standard error of the mean?

2.876

How many class !'s are correctly classified as Class 1 in the Table Below?

221

Suppose for a particular week, the forecasted sales were $4,000. The actual sales were $3,000. What is the value of the mean absolute percentage error?

33.3%

Within a given range of cells, the number of times a particular condition is satisfied is computed by using the ________ function.

COUNTIF

The ___________ is a measure of the goodness of fit of the estimated regression equation. It can be interpreted as the proportion of the variability in the dependent variable y that is explained by the estimated regression equation.

Coefficient of determination

__________ compares the number of actual Class 1 observations identified if considered in decreasing order of their estimated probability if randomly classified.

Cumulative lift

Applying descriptive statistics and data visualization to the training set to understand the data and assist in the selection of an appropriate technique is a part of

Data exploration

A large manufacturing plant has analyzed the amount of time required to produce an electrical part and determined that the times follow a normal distribution with mean time m=45 hours. The production manager has developed a new procedure for producing the part. He believes that the new procedure will decrease the population mean amount of time required to produce the part. After training a group of production line workers, a random sample of 25 parts will be selected and the average amount of time required to produce them will be determined. If the switch is made to the new procedure, the cost to implement the new procedure will be more than offset by the savings in manpower required to produce the parts. Use the hypotheses : Ho: m>_45 hours and Ha: m< 45 hours. If the sample mean amount of time is =43.118 hours with the sample standard deviation s=5.5 hours, give the appropriate conclusion, for a = 0.025

Do not reject H0, do not switch to the new procedure

Which statement is NOT true?

Failing to reject the null hypothesis when it is false is a Type I error.

The average number of hours for a random sample of mail order pharmacists from company A was 50.1 hours last year. It is believed that changes to medical insurance have led to a reduction in the average work week. To test the validity of this belief the hypotheses are

H 0: u ≤ 50.1, Ha: u > 50.1.

Which of the following is true of the exponential smoothing coefficient?

It is chosen as the value that minimizes a selected measure if forecast accuracy such as the mean squared error

The set of recorded values of variables associated with a single entity is a(n)

Observation

What do nodes in an influence diagram represent?

Parts of the model

Which of the following regression models is used to model a nonlinear relationship between the independent variable and the square of the independent variable in the model?

Quadratic regression model

_________ is a stat procedure used to develop an equation showing how two variables are related.

Regression analysis

What are the two decisions that you can make from performing a hypothesis test?

Reject the null hypothesis; Fail to reject the null hypothesis

Which statement is not true?

Rejecting the null hypothesis when it is true is a Type II error.

The ___________ button in the Formula Auditing group allows the user to inspect each formula in detail in its cell location.

Show formulas

In the graph of the simple linear regression equation the parameter ß1 is the ___________ of the true regression line.

Slope

_________ is one minus the Class 0 error rate.

Specificity

With reference to the SUMPRODUCT function, which of the following statements is true?

The arrays that appear as arguments must be of the same dimension

Which of the following approaches is a good way to proceed with the influence diagram building for a problem

The influence diagram for a portion of the problem is built first and then expanded until the total problem is conceptually modeled.

Which of the following states the objective of time series analysis?

To uncover a pattern in a time series and then extrapolate the pattern into the future

Which of the following would be a likely mathematical expression for Total Revenue?

Total Revenue = Production Volume × Revenue per Unit

The impact of two inputs on the output of interest is summarized by a

Two way data table

When the mean value of the dependent variable is independent of variation in the independent variable the slope of the regression line is

Zero

The moving averages and exponential smoothing methods are appropriate for a time series exhibiting

a horizontal pattern

The Watch Window is observable

across different worksheets of a workbook

Spreadsheet models are referred to as what-if models because they

allow easy instantaneous recalculation for a change in model inputs.

A normally distributed error term with a mean of zero would

allow more accurate modeling

For a population with an unknown distribution, the form of the sampling distribution of the sample mean is

approximately normal for large sample sizes

Which is not true regarding trend patterns?

can result when business conditions shift to a new level at some point in time

As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution

becomes smaller

Using an a= 0.04, a confidence interval for a population proportion is determined to be 0.65 to 0.75. If the level of significance is decreased, the interval for the population proportion

becomes wider

The modeling process begins with the framing of a _____ model that shows the relationships between the various parts of the problem being modeled

conceptual

In a linear regression model, the variable that is being predicted or explained is known as ______. It is denoted as y and is often referred to as the response variable.

dependent variable

Applying descriptive stats and data visualization to the training set to understand the dat and assist in the selection of an appropriate technique is a part of

data exploration

Classifying a record as belonging to one class when it belongs to another class is referred to as a(n)

error

In the simple linear regression mode, the ________accounts for the variability in the dependent variable that cannot be explained by the linear relationship between the variables

error term

A test set is the data set used to

estimate performance of the final model on unseen data

Determine a freshman's likely first-year grade point average from the student's Scholastic Aptitude test (SAT) score, HS GPA, and number of extra-curricular activities. This is an example of

estimation of a continuous outcome

Which of the following tools provides an excellent means of identifying the exact location of an error in a formula

evaluate formula

Forecast error

is associated with measuring forecast accuracy.

The coefficient of determination

is used to evaluate the goodness of fit

The prespecified value of the independent variable at which its relationship with the dependent variable changes in a piecewise linear regression model is referred to as the

knot.

Statistical significance as the 0.01 level is __________ than significance at the 0.05 level.

more difficult to achieve

A time series plot of a period of time (in years) versus revenue (in millions of dollars) is shown below. Which of the following data patterns best describes the scenario shown?

nonlinear trend pattern

The set of recorded values of variables associated with a single entity is a(n)

observation

A simple random sample of 31 observations was taken from a large population. The sample mean equals 5. Five is a

point estimate

With reference to time series data patterns a cyclical pattern is the component of the time series that

shows a periodic pattern lasting more than one year.

In a simple linear regression analysis the quantity that gives the amount by which the dependent variable changes for a unit change in the independent variable is called

slope of the regression line

The least squares regression line minimizes the sum of the

squared differences between actual and predicted y values

Data Mining methods for classifying or estimating an outcome based on a set of input variables is referred to as

supervised learning

The x-axis of a lift chart shows

the number of actual Class 1 records identified.

If a time series plot exhibits a horizontal pattern, then

there is still not enough evidence to conclude that the time series is stationary

A set of observations on a variable measured at successive points in time or over successive periods of time constitute a

time series

The moving averages method refers to a forecasting method that

uses the average of the most recent data values in the time series as the forecast for the next period.

A characteristic or quantity of interest that can take on different values is a(n)

variable