What does the “Loss” value given by Keras mean?












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I setup my neural net to use mean square error as shown below. To my understanding (and from reading the documentation) this means that if the correct result of a row is 0.7 and the net predicts 0.8 the contribution to the loss by this entry is (0.8 - 0.7) squared = 0.01



from keras.models import Sequential
from keras.layers import Dense

#...build up neural network layers here...

net.compile(optimizer = 'adam', loss = 'mean_squared_error')
net.fit(training_data, training_results, batch_size = 4, epochs = 100)


I get the following output.



Epoch 100/100
1190/1190 [==============================] - 0s 133us/step - loss: 0.0082



Wow the the loss is tiny, my little neural network is doing so well! However if I validate the result on my original training data



prediction = net.predict(training_data)
prediction_delta = (prediction - training_results)


Although some of the values in the prediction_delta are small overall the loss is way higher than 0.0082 with single values as high as 0.44. Note that this is for the same training data used to fit the net and is not the test data (which also shows similar results) so I would expect to get the value 0.082 back. How does Keras calculate this loss number?










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    $begingroup$


    I setup my neural net to use mean square error as shown below. To my understanding (and from reading the documentation) this means that if the correct result of a row is 0.7 and the net predicts 0.8 the contribution to the loss by this entry is (0.8 - 0.7) squared = 0.01



    from keras.models import Sequential
    from keras.layers import Dense

    #...build up neural network layers here...

    net.compile(optimizer = 'adam', loss = 'mean_squared_error')
    net.fit(training_data, training_results, batch_size = 4, epochs = 100)


    I get the following output.



    Epoch 100/100
    1190/1190 [==============================] - 0s 133us/step - loss: 0.0082



    Wow the the loss is tiny, my little neural network is doing so well! However if I validate the result on my original training data



    prediction = net.predict(training_data)
    prediction_delta = (prediction - training_results)


    Although some of the values in the prediction_delta are small overall the loss is way higher than 0.0082 with single values as high as 0.44. Note that this is for the same training data used to fit the net and is not the test data (which also shows similar results) so I would expect to get the value 0.082 back. How does Keras calculate this loss number?










    share|improve this question







    New contributor




    user67342 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.







    $endgroup$















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      0





      $begingroup$


      I setup my neural net to use mean square error as shown below. To my understanding (and from reading the documentation) this means that if the correct result of a row is 0.7 and the net predicts 0.8 the contribution to the loss by this entry is (0.8 - 0.7) squared = 0.01



      from keras.models import Sequential
      from keras.layers import Dense

      #...build up neural network layers here...

      net.compile(optimizer = 'adam', loss = 'mean_squared_error')
      net.fit(training_data, training_results, batch_size = 4, epochs = 100)


      I get the following output.



      Epoch 100/100
      1190/1190 [==============================] - 0s 133us/step - loss: 0.0082



      Wow the the loss is tiny, my little neural network is doing so well! However if I validate the result on my original training data



      prediction = net.predict(training_data)
      prediction_delta = (prediction - training_results)


      Although some of the values in the prediction_delta are small overall the loss is way higher than 0.0082 with single values as high as 0.44. Note that this is for the same training data used to fit the net and is not the test data (which also shows similar results) so I would expect to get the value 0.082 back. How does Keras calculate this loss number?










      share|improve this question







      New contributor




      user67342 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.







      $endgroup$




      I setup my neural net to use mean square error as shown below. To my understanding (and from reading the documentation) this means that if the correct result of a row is 0.7 and the net predicts 0.8 the contribution to the loss by this entry is (0.8 - 0.7) squared = 0.01



      from keras.models import Sequential
      from keras.layers import Dense

      #...build up neural network layers here...

      net.compile(optimizer = 'adam', loss = 'mean_squared_error')
      net.fit(training_data, training_results, batch_size = 4, epochs = 100)


      I get the following output.



      Epoch 100/100
      1190/1190 [==============================] - 0s 133us/step - loss: 0.0082



      Wow the the loss is tiny, my little neural network is doing so well! However if I validate the result on my original training data



      prediction = net.predict(training_data)
      prediction_delta = (prediction - training_results)


      Although some of the values in the prediction_delta are small overall the loss is way higher than 0.0082 with single values as high as 0.44. Note that this is for the same training data used to fit the net and is not the test data (which also shows similar results) so I would expect to get the value 0.082 back. How does Keras calculate this loss number?







      machine-learning neural-network deep-learning keras






      share|improve this question







      New contributor




      user67342 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.











      share|improve this question







      New contributor




      user67342 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









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      user67342 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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