Coursera Deep Learning 2 改善深层神经网络：超参数调试、正则化以及优化 第一周习题

Practical aspects of Deep Learning

代码见博主 Github

1

if you have 10,000,000 examples, how would you split the train/dev/test set?

60% train . 20% dev . 20% test

98% train . 1% dev . 1% test
正确

33% train . 33% dev . 33% test

2

The dev and test set should:

Come from the same distribution
正确

Come from different distributions

Be identical to each other (same (x,y) pairs)

Have the same number of examples

3

If your Neural Network model seems to have high variance, what of the following would be promising things to try?

Get more test data
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Add regularization
正确

Make the Neural Network deeper
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Get more training data
正确

Increase the number of units in each hidden layer
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4

You are working on an automated check-out kiosk for a supermarket, and are building a classifier for apples, bananas and oranges. Suppose your classifier obtains a training set error of 0.5%, and a dev set error of 7%. Which of the following are promising things to try to improve your classifier? (Check all that apply.)

Increase the regularization parameter lambda
正确

Decrease the regularization parameter lambda
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Get more training data
正确

Use a bigger neural network
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5

What is weight decay?

A regularization technique (such as L2 regularization) that results in gradient descent shrinking the weights on every iteration.
正确

A technique to avoid vanishing gradient by imposing a ceiling on the values of the weights.

Gradual corruption of the weights in the neural network if it is trained on noisy data.

The process of gradually decreasing the learning rate during training.

6

What happens when you increase the regularization hyperparameter lambda?

Weights are pushed toward becoming smaller (closer to 0)
正确

Weights are pushed toward becoming bigger (further from 0)

Doubling lambda should roughly result in doubling the weights

Gradient descent taking bigger steps with each iteration (proportional to lambda)

7

ith the inverted dropout technique, at test time:

You do not apply dropout (do not randomly eliminate units), but keep the 1/keep_prob factor in the calculations used in training.

You apply dropout (randomly eliminating units) and do not keep the 1/keep_prob factor in the calculations used in training

正确

You apply dropout (randomly eliminating units) but keep the 1/keep_prob factor in the calculations used in training.

You do not apply dropout (do not randomly eliminate units) and do not keep the 1/keep_prob factor in the calculations used in training

8

Increasing the parameter keep_prob from (say) 0.5 to 0.6 will likely cause the following: (Check the two that apply)

Increasing the regularization effect
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Reducing the regularization effect
正确

Causing the neural network to end up with a higher training set error
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Causing the neural network to end up with a lower training set error
正确

9

Which of these techniques are useful for reducing variance (reducing overfitting)? (Check all that apply.)

Data augmentation
正确

Exploding gradient
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L2 regularization
正确

Gradient Checking
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Xavier initialization
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Dropout
正确

Vanishing gradient
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10

Why do we normalize the inputs x?

It makes the parameter initialization faster

It makes it easier to visualize the data

It makes the cost function faster to optimize
正确

Normalization is another word for regularization--It helps to reduce variance