pg. 1 2025 ISYE 6501 Midterm Exam Practice Guide with 250 Questions and Correct Answers/ ISYE 6501 latest 2025-2026 Midterm Practice Test with Correct Answers
What will Regression tell you?How systems work (descriptive questions) and what will happen in the future (prescriptive questions) How is the best fit regression line determined?It is the line that minimizes the sum of squared errors
How do we find the best value of k in k means?
Elbow method: we calculate the total distance of each data point to its cluster
center and plot it in two dimensions. We look for the k in k in the graph.
When clustering for prediction how do we choose the prediction?When we see a new point, we just choose whichever cluster center is closest.what is the general equation for p-norm distance
2-norm 1 / 3
pg. 2 Straight-line distance corresponds to which distance metric?
How do you find the distance of an infinity norm?You find the largest | x_i - y_i | What is a centroid the center of a cluster Which of these is generally a good reason to remove an outlier from your data set?
- The outlier is an incorrectly-entered data, not real data.
- Outliers like this only happen occasionally.
A.
If the data point isn't a true one, you should remove it from your data set.What is an outlier?A data point that is very different from the rest What graph or plot can we use to find outliers?box-and-whisker plot What are the parts of a box-and-whisker plot?The bottom and top of the box are the 25th and 75th percentile. The middle valu is the median. The whiskers stretch up and down to reasonable range of values (10 and 90th or 5th and 95 percentiles) Where would outliers exist in a box and whisker plot outside of the whiskers.What are some ways to deal with outliers that are bad data?Omit them or use imputation 2 / 3
pg. 3 What can change detection be used for?Determining whether action might be needed, determining impact of past action, determining changes to help plan.What is Cumulative sum (CUSUM) used for detect in crease, decrease or both What is C used for in the Cusum formula Since we expect there to be some randomness, we include a value C to pull the running total down
If we have a larger C ...the harder for S_t to get large and the less sensitive the method will be If we have a smaller C ...the more sensitive the method is because S_t can get larger faster What factors go into finding the right values of C and T?how costly it is if the model takes a long time to nice a change, and how costly it is if the model think it has found a change that really isn't there.Why are hypothesis tests often not sufficient for change detection?They often are slow to detect changes.
Hypothesis tests generally have high threshold levels, which makes them slow to detect changes.In the CUSUM model, having a higher threshold T makes it...detect changes slower, and less likely to falsely detect changes.In the exponential smoothing equation S_t = \alpha \times x_t + (1-\alpha) \times S_{t-1} a value of closer to 1 is chosen if...
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