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AI/ML Glossary

This page contains definitions for terms used when talking about artificial intelligence and machine learning. Use it as a reference as you learn, build, and fine-tune how to use AI in Appian.

A

Accuracy

Accuracy is the ratio of correct predictions to total predictions, expressed as a percentage. It is a broader metric than precision and recall and may give you more general insight into how your model is performing.

Accuracy is calculated as:

True positives + True negatives

divided by

True positives + true negatives + false positives + false negatives

Actual type

In document or email classification AI skills, the actual type is the document or email's type in reality.

When you create a model, you configure document or email types according to the categories you want to classify, such as invoices or purchase orders. Then, you'll upload documents or emails that represent each type, such as example invoices you've received in the past. Because you upload samples of the type of document or emails you want to classify, the model knows that this is the actual type as it uses them for training and testing.

In production, the actual type determines if the model's guess (predicted type) was correct or not.

For example, if the model predicted a document is invoice but the actual type is a purchase order, the prediction is incorrect.

Algorithm

Code-based procedures designed to solve a specific problem. In artificial intelligence, a model is constructed of one or multiple algorithms that can be used together to serve a specific purpose.

Artificial intelligence

Artificial intelligence (AI) is a computer's capacity for intelligence that mimics a human's or animal's. In other words, AI is a computer's ability to perform tasks and higher order reasoning beyond what it's explicitly programmed to do. It uses machine learning to improve this capacity.

C

Confidence score

A measure of how sure an ML model is of its predictions. When classifying documents or emails in Appian, the model returns a confidence score for each prediction it makes.

Confusion matrix

A confusion matrix visually represents how the model performed in terms of predicted types vs. actual types.

The confusion matrix grows larger based on the number of document or email types within the model. Because the confusion matrix plots the predicted types against the actual types, you want to see high values on the diagonal cells. Higher numbers in the diagonal indicate that the predicted type matches the actual type, and the model is correctly classifying documents or emails.

D

Data set

The collection of information a developer sends to a model as a basis for training. In the case of document or email classification, the data set is a collection of documents or emails that represent those the model would expect to encounter in production.

F

False positive

When a model incorrectly predicts that a trait of interest is present in the data.

For example, a model is trained to predict either stop signs or cars in images it analyzes. The model analyzes an image and predicts it contains a car, but the image actually contains a stop sign. This prediction is a false positive with respect to the car class, and a false negative with regards to the stop sign.

False negative

When a model incorrectly predicts that a trait of interest is not present in the data, but it is.

For example, a model is trained to predict either stop signs or cars in images it analyzes. The model analyzes an image and predicts it contains a car, but the image actually contains a stop sign. This prediction is a false positive with respect to the car class, and a false negative with regards to the stop sign.

F-1 Score

A metric used to measure accuracy in machine learning. The F-score (aka F1-score) is a quick way to understand the model's ability to fulfill its purpose and make correct predictions. It is computed using precision and recall.

M

Model

A model is the product of combining a data set with a machine learning algorithm. A model is unique to a purpose which requires recognition, understanding, reasoning, and decision-making. For example, the model used to classify purchase orders isn't necessarily the same one that can recognize stop signs in a set of pictures.

Machine learning

The pursuit and practice of building software that seeks to improve its artificial intelligence independently. Machine learning (ML) enables computers to learn from experience and improve future performance without being programmed to do so.

O

Overfitting

Overfitting is when a model is trained too specifically on test data, to the point that it looks for very specific patterns and can't detect patterns in real data.

For example, imagine you are training a model with a data set that contains 100 invoices. These invoices are examples of ones your business has received in the past. If you train the model too much on this data set (trying to reach 100% accuracy), it's possible that the model won't be able to adapt and detect invoices that look differently in production than the invoices in your test data set.

Outcomes

The four categories the model's predictions can fall into, when compared to reality:

Term Prediction Reality
True positive Image contains a stop sign Image contains a stop sign
True negative Image doesn't contain a stop sign Image doesn't contain a stop sign
False positive Image contains a stop sign Image doesn't contain a stop sign
False negative Image doesn't contain a stop sign Image contains a stop sign

P

Precision

Precision is expressed as a value between 0 and 1, which indicates the number of true positive predictions the model made, compared to the total number of positive identifications (including those that are false). In other words, it answers the question: out of all of the positive guesses, how many were correct?

For example, a model is given 10 documents and tasked with identifying how many of them are invoices. There are 4 invoices in the set of documents, but the model positively identifies only 3. However, those 3 identifications are correct (true positives). In this example, the model's precision is 1.0 because all of its predictions were correct (no false positives), even though it didn't identify all of the invoices.

Precision is closely related to recall, and together they calculate the F-1 Score.

Precision is calculated as:

True positives

divided by

True positives + false positives

Predicted type

In document classification AI skills, the predicted type is the output of the model's analysis of a document. The model attempts to classify documents based on the document types that were used to train the skill.

Simply put, the predicted type is the model's guess when classifying a document. For example, "invoice" or "purchase order." The actual type determines if the model's guess (predicted type) was correct or not.

For example, if the model predicted a document is invoice but the actual type is a purchase order, the prediction is incorrect.

R

Recall

Recall is the number of actual correct predictions a model made. Unlike precision, recall also considers the number of correct predictions the model didn't make. It answers the question: out of all of the guesses, how many were correct positive predictions?

For example, a model is given 10 documents and tasked with identifying how many of them are invoices. There are 4 invoices in the set of documents, but the model identifies only 3. However, those 3 identifications are correct (true positives). It missed identifying 1 invoice (false negative). In this example, the model's recall is .75 because it missed predicting one of the invoices.

Recall is closely related to precision, and together they calculate the F-1 Score.

Recall is calculated as:

True positives

divided by

True positives + false negatives

T

True positive

When a model correctly predicts that a trait of interest is present in the data. For example, if the model predicts that an image contains a stop sign, and it actually does, this prediction would be categorized as a true positive.

True negative

When a model correctly predicts that a trait of interest is not present in the data. For example, if the model predicts that an image doesn't contain a stop sign, and it doesn't, this prediction would be categorized as a true negative.

AI/ML Glossary