OPSY 5315 Operations Management Exam 2 | Forecasting,
Quality & Practice Questions with Detailed Rationales
2026/2027
Question 1
In time-series forecasting, what is the primary assumption of the
"naïve" approach?
• A. Future demand will be calculated using complex multiple
regression.
• B. The forecast for the next period is simply the actual demand
from the most recent period.
• C. Seasonality and trends are perfectly predictable.
• D. Inventory costs are zero.
Correct Answer: B. The forecast for the next period is simply the actual
demand from the most recent period.
Detailed Rationale: The naïve method is the simplest forecasting
model. It assumes that tomorrow's demand will be identical to today's,
which is often used as a baseline to evaluate the performance of more
sophisticated models.
Question 2
What is the "trend" component in a time-series forecast?
• A. Random noise that cannot be predicted.
, • B. The persistent upward or downward movement in data over a
long period.
• C. A recurring pattern that repeats every 24 hours.
• D. The specific effect of a marketing promotion.
Correct Answer: B. The persistent upward or downward movement in
data over a long period.
Detailed Rationale: Trends are long-term movements in data, typically
caused by factors like economic growth, changes in population, or
shifting consumer preferences.
Question 3
Why is the Mean Absolute Percentage Error (MAPE) often preferred
over Mean Absolute Deviation (MAD) for comparing forecast accuracy
across products?
• A. MAPE is calculated in units, while MAD is calculated in dollars.
• B. MAPE is a percentage, making it scale-independent and useful
for comparing accuracy across different volume levels.
• C. MAPE is always zero for perfect forecasts.
• D. MAPE is easier to calculate by hand than MAD.
Correct Answer: B. MAPE is a percentage, making it scale-independent
and useful for comparing accuracy across different volume levels.
Detailed Rationale: Because MAD is expressed in units, it cannot be
compared between a product selling 100 units/year and one selling
1,000,000 units/year. MAPE standardizes the error as a percentage,
allowing for direct comparison.
,Question 4
In exponential smoothing, what does an alpha (𝛼) value of 0.8 imply?
• A. The model relies heavily on historical data from years ago.
• B. The forecast will be extremely smooth and react slowly to
recent changes.
• C. The forecast is highly responsive to the most recent actual
demand.
• D. The model is statistically invalid.
Correct Answer: C. The forecast is highly responsive to the most recent
actual demand.
Detailed Rationale: In exponential smoothing (𝐹𝑡 = 𝐹𝑡−1 +
𝛼 (𝐴𝑡−1 − 𝐹𝑡−1 )), a high alpha gives more weight to the most recent
actual observation, causing the forecast to track recent changes closely.
Question 5
What is the difference between a "dependent" and "independent"
variable in linear regression forecasting?
• A. The independent variable is the one being forecast (the
output); the dependent variable is the predictor.
• B. The dependent variable is the one being forecast (the output);
the independent variable is the predictor.
• C. There is no difference; they are interchangeable.
• D. Dependent variables are only used in qualitative forecasting.
, Correct Answer: B. The dependent variable is the one being forecast
(the output); the independent variable is the predictor.
Detailed Rationale: In the equation 𝑦 = 𝑎 + 𝑏𝑥, 𝑦is the dependent
variable (the demand we want to predict), and 𝑥is the independent
variable (the factor we believe influences demand, like time or price).
Question 6
What is the "tracking signal" used to monitor in a forecasting system?
• A. The exact location of a delivery truck.
• B. Bias in the forecast (i.e., whether the forecast is consistently
overestimating or underestimating demand).
• C. The speed at which a product is manufactured.
• D. The physical size of the warehouse.
Correct Answer: B. Bias in the forecast (i.e., whether the forecast is
consistently overestimating or underestimating demand).
Detailed Rationale: A tracking signal (𝑆𝑢𝑚 𝑜𝑓 𝐹𝑜𝑟𝑒𝑐𝑎𝑠𝑡 𝐸𝑟𝑟𝑜𝑟𝑠/𝑀𝐴𝐷)
identifies if the model is drifting. If it exceeds predetermined control
limits, the forecasting model is biased and needs adjustment.
Question 7
Which of the following is considered a qualitative forecasting method?
• A. Time-series decomposition.
• B. Delphi Method.
• C. Linear regression.
• D. Exponential smoothing.
Quality & Practice Questions with Detailed Rationales
2026/2027
Question 1
In time-series forecasting, what is the primary assumption of the
"naïve" approach?
• A. Future demand will be calculated using complex multiple
regression.
• B. The forecast for the next period is simply the actual demand
from the most recent period.
• C. Seasonality and trends are perfectly predictable.
• D. Inventory costs are zero.
Correct Answer: B. The forecast for the next period is simply the actual
demand from the most recent period.
Detailed Rationale: The naïve method is the simplest forecasting
model. It assumes that tomorrow's demand will be identical to today's,
which is often used as a baseline to evaluate the performance of more
sophisticated models.
Question 2
What is the "trend" component in a time-series forecast?
• A. Random noise that cannot be predicted.
, • B. The persistent upward or downward movement in data over a
long period.
• C. A recurring pattern that repeats every 24 hours.
• D. The specific effect of a marketing promotion.
Correct Answer: B. The persistent upward or downward movement in
data over a long period.
Detailed Rationale: Trends are long-term movements in data, typically
caused by factors like economic growth, changes in population, or
shifting consumer preferences.
Question 3
Why is the Mean Absolute Percentage Error (MAPE) often preferred
over Mean Absolute Deviation (MAD) for comparing forecast accuracy
across products?
• A. MAPE is calculated in units, while MAD is calculated in dollars.
• B. MAPE is a percentage, making it scale-independent and useful
for comparing accuracy across different volume levels.
• C. MAPE is always zero for perfect forecasts.
• D. MAPE is easier to calculate by hand than MAD.
Correct Answer: B. MAPE is a percentage, making it scale-independent
and useful for comparing accuracy across different volume levels.
Detailed Rationale: Because MAD is expressed in units, it cannot be
compared between a product selling 100 units/year and one selling
1,000,000 units/year. MAPE standardizes the error as a percentage,
allowing for direct comparison.
,Question 4
In exponential smoothing, what does an alpha (𝛼) value of 0.8 imply?
• A. The model relies heavily on historical data from years ago.
• B. The forecast will be extremely smooth and react slowly to
recent changes.
• C. The forecast is highly responsive to the most recent actual
demand.
• D. The model is statistically invalid.
Correct Answer: C. The forecast is highly responsive to the most recent
actual demand.
Detailed Rationale: In exponential smoothing (𝐹𝑡 = 𝐹𝑡−1 +
𝛼 (𝐴𝑡−1 − 𝐹𝑡−1 )), a high alpha gives more weight to the most recent
actual observation, causing the forecast to track recent changes closely.
Question 5
What is the difference between a "dependent" and "independent"
variable in linear regression forecasting?
• A. The independent variable is the one being forecast (the
output); the dependent variable is the predictor.
• B. The dependent variable is the one being forecast (the output);
the independent variable is the predictor.
• C. There is no difference; they are interchangeable.
• D. Dependent variables are only used in qualitative forecasting.
, Correct Answer: B. The dependent variable is the one being forecast
(the output); the independent variable is the predictor.
Detailed Rationale: In the equation 𝑦 = 𝑎 + 𝑏𝑥, 𝑦is the dependent
variable (the demand we want to predict), and 𝑥is the independent
variable (the factor we believe influences demand, like time or price).
Question 6
What is the "tracking signal" used to monitor in a forecasting system?
• A. The exact location of a delivery truck.
• B. Bias in the forecast (i.e., whether the forecast is consistently
overestimating or underestimating demand).
• C. The speed at which a product is manufactured.
• D. The physical size of the warehouse.
Correct Answer: B. Bias in the forecast (i.e., whether the forecast is
consistently overestimating or underestimating demand).
Detailed Rationale: A tracking signal (𝑆𝑢𝑚 𝑜𝑓 𝐹𝑜𝑟𝑒𝑐𝑎𝑠𝑡 𝐸𝑟𝑟𝑜𝑟𝑠/𝑀𝐴𝐷)
identifies if the model is drifting. If it exceeds predetermined control
limits, the forecasting model is biased and needs adjustment.
Question 7
Which of the following is considered a qualitative forecasting method?
• A. Time-series decomposition.
• B. Delphi Method.
• C. Linear regression.
• D. Exponential smoothing.
