ISYE 6501 - Midterm 1 Questions and Answers 2023
What do descriptive questions ask?
What happened? (e.g., which customers are most alike)
What do predictive questions ask?
What will happen? (e.g., what will Google's stock price be?)
What do prescriptive questions ask?
What action(...
ISYE 6501 - Midterm 1 Questions and Answers 2023
What do descriptive questions ask? - answer What happened? (e.g., which customers are most alike)
What do predictive questions ask? - answer What will happen? (e.g., what will Google's stock price be?)
What do prescriptive questions ask? - answer What action(s) would be best? (e.g., where to put traffic lights)
What is a model? - answer Real-life situation expressed as math.
What do classifiers help you do? - answer differentiate
What is a soft classifier and when is it used? - answer In some cases, there won't be a line that separates all of the labeled examples. So we use a classifier that minimizes the number of mistakes.
What does it mean when the classifier/decision boundary is almost parallel to the vertical x-axis? - answer The horizontal attribute is all that is needed.
What does it mean when the classifier/decision boundary is almost parallel to the horizontal y-axis? - answer The vertical attribute is all that is needed.
What is time-series data? - answer The same data recorded over time often recorded at equal intervals
What is quantitative data? - answer Number with a meaning: higher means more, lower means less (e.g., age, sales, temperature, income)
What is categorical data? - answer Numbers w/o meaning (e.g., zip codes), non-
numeric (e.g., hair color), binary data (e.g., male/female, yes/no, on/off)
Which of these is time series data?
A. The average cost of a house in the United States every year since 1820
B. The height of each professional basketball player in the NBA at the start of the season - answer A
Which of these is structured data?
A. The contents of a person's Twitter feed
B. The amount of money in a person's bank account - answer B What is structured data? - answer Data that can be stores in a structured way
What is unstructured data? - answer Data that is not easily described and stored (e.g., written text)
A survey of 25 people recorded each person's family size and type of car. Which of these is a data point?
A. The 14th person's family size and car type
B. The 14th person's family size
C.The car type of each person - answer A. A data point is all the information about one observation
The farther the wrongly classified point is from the line ___ - answer The bigger the mistake we've made
The term including the margin gets larger so the importance of a large margin out weights avoiding mistakes and classifying known data samples. - answer As lambda gets larger
That term also drops towards zero, so the importance of minimizing mistakes and classifying known data points outweighs having a large margin. - answer As lambda drops towards zero
What can SVMs be used for - answer to find a classifier with maximum seperation or
margin between the two sets of points?
When to use SVM? - answer If it's impossible to avoid classification errors, SVM can find a classifier that trades off reducing errors and enlarging the margin.
Error for data point j - answer What does this formula describe?
Total error - answer What does this formula describe ?
To maximize the distance between the two lines what do we need to minimize? - answer m_j > 1 - answer What value do we give for more costly errors
Giving a bad loan is twice as costly as withholding a good loan? - answer What does
this mean in the context of giving a loan?
m_j < 1 - answer What value do we give for less costly errors?
Why is it important to scale our data when using SVM? - answer We're looking to minimize the sum of the squares of the coefficients, but if our data has very different scales a small change in one could swamp a huge change in the other. what does it signify when a coefficient for a classifier is close to zero - answer it means the corresponding attribute is probably not relevant
What do kernel methods allow for in SVMs - answer nonlinear classifiers
What is the common range for scaled data? - answer between 0 and 1
What is the formula for min-max scaling? - answer find min and max for a factor
what is common standardization and its formula? - answer scaling to a normal distribution with a mean of 0 and standard deviation of 1.
what is the formula for general scaling between b and a - answer When do you use scaling? - answer Data in a bounded range (e.g., neural networks, RGB values, SAT scores, batting averages)
When do you use standardization? - answer PCA or clustering
When is KNN used? - answer Used for solving classification problems in which there
are more than two classes.
How do you deal with attributes that might be more important than others in KNN? - answer You weight each dimension's distance different. The larger the weight the higher the impact.
A large value of K will lead to - answer a large variance in predictios
Setting a large value of k will ... - answer lead to a large model bias.
What are real effects? - answer Real relationships between attributes and responses. They are the same in all data sets,
What are random effects? - answer They are random but look like real effects. They are different in all data sets.
Why can't we measure a model's effectiveness on data it was trained on? - answer The model's performance on its training data is usually too optimistic, the model is fit to both real and random pattenrs in the data, so it becomes overly specialized to the specific randomness in the training set, that doesn't exist in other data.
If we use the same data to fit a model as we do to estimate how good it is, what is likely to happen? - answer The model will appear to be better than it really is.
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