MSCI 446 MIDTERM PRACTICE EXAM
UPDATED QUESTIONS AND CORRECT
ANSWERS.
What is unsupervised machine learning? - ANS -Explain the past - at face value, what does it
tell you?
o Not interested in learning the future
-Segmentation, association
What is supervised machine learning? - ANS -Predict the future based on the past given data
-Predict the value of some variable (past) using the values of other variables
How does email spam filtering work? - ANS Input: examples of legitimate emails and spam
emails
Output: a program that predicts whether a given email is legitimate or spam - could be very bad
depending on how general the learning is (i.e. keywords vs. exact sentences)
Explain One Hot Encoding - ANS Categorical -> Boolean/Binary: If the categorical variable has
k values, one hot encoding creates k Boolean variables, one of which will be true in any one
record
Explain Document Term Vectors - ANS o A fragment of vector from a short document with
text
o Unlocks machine learning algorithms that previously required numeric values
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
, o Consequence: Fails to recognize words that have similar semantics because they have
different spellings
o Bert model: word embeddings
What is an outcome? - ANS · The variable we want to predict
· If the outcome variable is categorical, we say we are doing classification
· Otherwise, we say we are doing numeric prediction
· Classifier: The algorithm for classification
What is a predictor? - ANS · The variables we will use to predict the outcome variable
· Also referred to as explanatory variable or features
What is a good feature? - ANS A good feature should be correlated with the label it predicts
What is garbage-in-garbage-out? - ANS Data Quality
o Duplicate data
o Incorrect data
o Missing data
What are some examples of garbage-in-garbage-out? - ANS a very high salary in a boxplot of
salaries -> owner/CEO is outlier,
employees age between 17 and 65,
definition of a 'trip' to track bikes,
GPS accuracy to within 100 meters,
salary on an hourly/weekly/annual basis,
temperature = 0,
default postal code
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
UPDATED QUESTIONS AND CORRECT
ANSWERS.
What is unsupervised machine learning? - ANS -Explain the past - at face value, what does it
tell you?
o Not interested in learning the future
-Segmentation, association
What is supervised machine learning? - ANS -Predict the future based on the past given data
-Predict the value of some variable (past) using the values of other variables
How does email spam filtering work? - ANS Input: examples of legitimate emails and spam
emails
Output: a program that predicts whether a given email is legitimate or spam - could be very bad
depending on how general the learning is (i.e. keywords vs. exact sentences)
Explain One Hot Encoding - ANS Categorical -> Boolean/Binary: If the categorical variable has
k values, one hot encoding creates k Boolean variables, one of which will be true in any one
record
Explain Document Term Vectors - ANS o A fragment of vector from a short document with
text
o Unlocks machine learning algorithms that previously required numeric values
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
, o Consequence: Fails to recognize words that have similar semantics because they have
different spellings
o Bert model: word embeddings
What is an outcome? - ANS · The variable we want to predict
· If the outcome variable is categorical, we say we are doing classification
· Otherwise, we say we are doing numeric prediction
· Classifier: The algorithm for classification
What is a predictor? - ANS · The variables we will use to predict the outcome variable
· Also referred to as explanatory variable or features
What is a good feature? - ANS A good feature should be correlated with the label it predicts
What is garbage-in-garbage-out? - ANS Data Quality
o Duplicate data
o Incorrect data
o Missing data
What are some examples of garbage-in-garbage-out? - ANS a very high salary in a boxplot of
salaries -> owner/CEO is outlier,
employees age between 17 and 65,
definition of a 'trip' to track bikes,
GPS accuracy to within 100 meters,
salary on an hourly/weekly/annual basis,
temperature = 0,
default postal code
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
