A model that predicts whether a message is spam or not spam is performing classification, while a model that predicts a house price is performing regression.
5 Classification Online Quiz Questions
Use this free practice quiz with 20 questions to review 5 Classification, test your knowledge, and prepare for your next test or exam.
A classifier assigns each support ticket to either “urgent” or “not urgent.” What kind of classification task is this?
- A
Multiclass classification
- B
Binary classification
- C
Regression
A message classifier uses words in each message as to help predict its category.
An email classifier labels a message as spam when its estimated spam probability exceeds 0.50. For a message with an estimated probability of 0.82, which label does it predict?
- A
Spam
- B
Not spam
- C
A numerical quantity rather than a category
Every classifier must use a straight-line decision boundary, even when its feature space has many dimensions.
- A
True
- B
False
What is the term for the location in feature space where a classifier's predicted class changes?
Select all statements that correctly describe how a model can form classification regions.
- A
A decision tree divides feature space through feature-based splits.
- B
A linear model must create an irregular boundary by consulting nearby labeled examples.
- C
A k-nearest neighbors classifier can form an irregular boundary from nearby labeled examples.
- D
A linear support vector machine always predicts by choosing the most common label among nearby examples.
An image model chooses among “cat,” “dog,” and “bird.” This is an example of .
Which classification model predicts the class most common among a new example's nearest labeled training examples?
Select all models whose classification strategies are described as making feature-based splits or predicting from nearby labeled training examples.
- A
Decision trees
- B
k-nearest neighbors
- C
Logistic regression
- D
Support vector machines
Which description best explains how logistic regression can produce a binary class prediction?
- A
It predicts the most common class among nearby labeled examples.
- B
It applies a sequence of feature-based rules to reach a class prediction.
- C
It estimates class probabilities that can be converted into labels using a threshold.
- D
It seeks a separating boundary, often aiming for a wide margin.
Explain how a classifier uses training examples to predict a category for a new example, and describe what its decision boundary represents.
Some classifiers provide a score or probability for each class rather than outputting only a final label.
- A
True
- B
False
An email classifier assigns the label “spam” when its estimated spam probability is above a chosen threshold. What can happen if the threshold is changed?
- A
It changes the example's features.
- B
It can change which examples receive the “spam” label.
- C
It turns classification into a prediction of a numerical quantity.
- D
It changes the model's training examples into unlabeled data.
A model uses labeled examples of messages to predict whether each new message is spam or not spam. Which description best identifies this task?
- A
It predicts a numerical quantity from the input features.
- B
It assigns the example to a category based on its features.
- C
It groups examples without using any labeled training examples.
- D
It changes the features until they match a target value.
On a plot of examples described by two features, what does the curve separating regions predicted as different classes represent?
- A
The set of training examples that have the most common label.
- B
A score that measures how many features an example has.
- C
The location where the predicted class changes from one class to another.
- D
The numerical quantity that a regression model predicts.
What is the classification term for the location in feature space where a model's predicted class changes?
An email classifier reaches its label by applying a sequence of rules about the message's features. Which model type best matches this approach?
- A
A decision tree
- B
A k-nearest neighbors classifier
- C
A logistic regression model
- D
A support vector machine
What classification model predicts a new example's class from the labels of its nearest labeled training examples?
A binary logistic regression model estimates a message's spam probability as 0.82 and uses a threshold of 0.50. Which label does it predict?
- A
It predicts not spam because the probability is below 1.00.
- B
It predicts spam because 0.82 exceeds the 0.50 threshold.
- C
It cannot predict a label because logistic regression only produces features.
- D
It predicts not spam because the threshold is lower than the probability.