Consider the Following Code and Output: in [57]: for K

question 27

Multiple Choice

Consider the following code and output: In [57]: for k in range(1, 20, 2) :
) ..: kfold = KFold(n_splits=10, random_state=11, shuffle=True)
) ..: knn = KNeighborsClassifier(n_neighbors=k)
) ..: scores = cross_val_score(estimator=knn,
) ..: X=digits.data, y=digits.target, cv=kfold)
) ..: print(f'k={k:<2}; mean accuracy={scores.mean() :.2%}; ' +
) ..: f'standard deviation={scores.std() :.2%}')
) ..:
K=1 ; mean accuracy=98.83%; standard deviation=0.58%
K=3 ; mean accuracy=98.78%; standard deviation=0.78%
K=5 ; mean accuracy=98.72%; standard deviation=0.75%
K=7 ; mean accuracy=98.44%; standard deviation=0.96%
K=9 ; mean accuracy=98.39%; standard deviation=0.80%
K=11; mean accuracy=98.39%; standard deviation=0.80%
K=13; mean accuracy=97.89%; standard deviation=0.89%
K=15; mean accuracy=97.89%; standard deviation=1.02%
K=17; mean accuracy=97.50%; standard deviation=1.00%
K=19; mean accuracy=97.66%; standard deviation=0.96%
Which of the following statements is false?

• A) The loop creates KNeighborsClassifiers with odd k values from 1 through 19 and performs k-fold cross-validation on each.
• B) The k value 7 in kNN produces the most accurate predictions for the Digits dataset.
• C) The accuracy tends to decrease for higher k values.
• D) Compute time grows with k, because k-NN needs to perform many more calculations to find the nearest neighbors.

---

Definitions:

Average Total Cost

The cost per unit of output, found by dividing the total cost (fixed plus variable) by the number of units produced.

Cigars

Rolled bundles of dried and fermented tobacco leaves designed to be smoked.

ATC and MC Curves

Graphs in economics that represent a firm's average total costs (ATC) and marginal costs (MC) at different levels of production.

Tax

Mandatory financial charge or other levy imposed upon a taxpayer by a governmental organization in order to fund government spending and various public expenditures.