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
