Machine Learning 8 Best Ways to Improve Accuracy of ML Models

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Making assumptions about new data based on old data is what machine learning is all about. The accuracy of those predictions is essentially what determines the quality of any machine-learning algorithm. It is easy to “game” the accuracy metric when making predictions for a dataset like this. To do that, you simply need to predict that nothing will happen and label every email as non-spam. The model predicting the majority (non-spam) class all the time will mostly be right, leading to very high accuracy. Precision is defined as the ratio of correctly classified positive samples to a total number of classified positive samples .

what is accuracy in machine learning

To sum up, assessing a machine learning model’s loss and accuracy is a crucial stage in the machine learning process. The model’s performance can be evaluated, modifications can be made with knowledge, and the problem can be solved as intended can all be done by developers and data scientists. These negatives aspects of accuracy are reasons to be cautious of using it on your project. Accuracy should only be used on balanced datasets and in the context of other metrics that provide other aspects of the machine learning model’s performance.

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Accuracy can be useful for real-life applications too, when datasets with similar characteristics are available. Basically, to decide what metric to use, you need to be clear about exactly what is important for your application, and chose the metric accordingly. The mistake is to think there is a “one-size-fits-all” solution to the problem, and it is best to think hard about which metrics are appropriate for each application and why. For the previous example , classifying all as negative gives 0.5 balanced accuracy score , which is equivalent to the expected value of a random guess in a balanced data set. Balanced accuracy can serve as an overall performance metric for a model, whether or not the true labels are imbalanced in the data, assuming the cost of FN is the same as FP.

You want to ensure that the user never misses an important email because it is incorrectly labeled as spam. Accuracy, precision, and recall help evaluate the quality of classification models in machine learning. Each metric reflects a different aspect of the model quality, and depending on the use case, you might prefer one or another. Hence, in the last scenario, we have a precision value of 1 or 100% when all positive samples are classified as positive, and there is no any Negative sample that is incorrectly classified. But before starting, first, we need to understand the confusion matrix concept.

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Build ModelsTrain hundreds of modeling strategies in parallel using structured and unstructured data. Imagine that you are given an image and asked to detect all the cars within it. This may misclassify some objects as cars, but it eventually will work towards detecting all the target objects. Note that the order of the metrics differ from that discussed previously. For example, the True Positive metric is at the bottom-right corner while True Negative is at the top-left corner.

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The real problem arises, when the cost of misclassification of the minor class samples are very high. If we deal with a rare but fatal disease, the cost of failing to diagnose the disease of a sick person is much higher than the cost of sending a healthy person to more tests. For example, if the data is highly imbalanced (e.g. 90% of all players do not get drafted and 10% do get drafted) then F1 score will provide a better assessment of model performance. Most of the time we would observe that accuracy increases with the decrease in loss — but this is not always the case. Accuracy and loss have different definitions and measure different things. They often appear to be inversely proportional but there is no mathematical relationship between these two metrics.


Fortunately, there are several tools you can use to address this. Report Opens a new window, 22% of companies are early stage adopters with models in production for less than two years. Meanwhile, the business benefits of ML are increasingly apparent. 37% of those surveyed for Algorithmia’s report said they want to use ML for customer intelligence, 38% want to reduce costs, and 30% are looking to automate internal processes through ML technology. A model with a higher F1 Score, or a model with a higher AUC is a better model on the validation set. Once we run the models and look at accuracy with our tuned hyper parameters on our test set, we can then run it on our validate set.

what is accuracy in machine learning

Some algorithms are better suited to a particular type of data set than others. Hence, we should apply all relevant models and check the performance. Pursuing high accuracy and KPIs is a common goal in machine learning, but achieving 100% accuracy, or any other metric, as we’ve stated earlier, can be concerning for several reasons. It measures the proportion of correct predictions made by the model compared to the total number of predictions.

Interpreting Loss and Accuracy

A rigorous statement of accuracy includes statistical measures of uncertainty and variation. Accuracy is generally represented by standard deviation of errors . For example, if we say that a model is 90% accurate, we know that it correctly classified 90% of observations. A loss function, also known as a cost function, takes into account the probabilities or uncertainty of a prediction based on how much the prediction varies from the true value. This gives us a more nuanced view into how well the model is performing.

what is accuracy in machine learning

For example, in churn prediction, you can measure the cost of false negatives (i.e., failing to identify a customer who is likely to churn) as the lost revenue from this customer. Precision and Recall are the two most important but confusing concepts in Machine Learning. Precision and recall are performance metrics used for pattern recognition and classification in machine learning. These concepts are essential to build a perfect machine learning model which gives more precise and accurate results. Some of the models in machine learning require more precision and some model requires more recall. So, it is important to know the balance between Precision and recall or, simply, precision-recall trade-off.

What are the disadvantages of accuracy?

When a model has high recall but low precision, then the model classifies most of the positive samples correctly but it has many false positives (i.e. classifies many Negative samples as Positive). When a model has high precision but low recall, then the model is accurate when it classifies a sample as Positive but it can only classify what is accuracy a few positive samples. Classification Threshold In probabilistic machine learning problems, the model output is not a label but a score. You must then set a decision threshold to assign a specific label to a prediction. This chapter explains how to choose an optimal classification threshold to balance precision and recall.

  • The precision considers when a sample is classified as Positive, but it does not care about correctly classifying all positive samples.
  • The order of the matrices match the order of the labels in the labels parameter.
  • Precision is the fraction of relevant instances among the retrieved instances, while recall is the fraction of relevant instances that were retrieved.
  • One of the main reasons why model accuracy is an important metric, as previously highlighted, is that it is an extremely simple indicator of model performance.
  • Developers and data scientists can prevent overfitting by carefully weighing the model’s hyperparameters while monitoring the model’s accuracy and loss on the validation set.

Accuracy shows how often a classification ML model is correct overall. Confusion Matrix helps us to display the performance of a model or how a model has made its prediction in Machine Learning. It’s also possible to bias a model by trying to teach it to perform a task without presenting all of the necessary information. If you know the constraints of the model are not biasing the model’s performance yet you’re still observed signs of underfitting, it’s likely that you are not using enough features to train the model. The R2 coefficient represents the proportion of variance in the outcome that our model is capable of predicting based on its features.

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If all transactions are classified as not fraudulent, prediction accuracy is 99.97%. Model performance seems to be almost perfect, but the classifier is actually useless, as it does not flag any real fraudulent transaction. One of the main reasons why model accuracy is an important metric, as previously highlighted, is that it is an extremely simple indicator of model performance. We have not mentioned yet that it is also a simple measure of model error. Starting from the confusion matrix, we can see this relationship by deriving the statistical formula for accuracy. Note that we do so on binary classification for simplicity, but the same concept can be easily extended to more than two classes.


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