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What is sentiment analysis?

Yael Kurz
Yael Kurz
Jan 27, 2023
3 min read


As a data-driven business owner, you are always looking for ways to gain an advantage and improve your customer service. Sentiment analysis is a powerful tool that can help you achieve that. By analyzing customer feedback, be it in the form of emails, social media posts, or online reviews, you can gain a deeper understanding of customer sentiment and make improvements to your products or services.

For example, imagine you are running a food delivery service and want to gauge customer satisfaction with your service. By using sentiment analysis, you can track customer reviews and identify key themes and sentiments. This can help you identify potential issues, address complaints, and make necessary adjustments to improve customer satisfaction. Sentiment analysis can also be used to monitor the effectiveness of your marketing campaigns, by analyzing customer feedback on your advertisements.

Sentiment analysis is a powerful tool for data-driven business owners to improve customer service by analyzing customer feedback from various sources. By identifying key themes and sentiments, businesses can make necessary adjustments to improve customer satisfaction, address complaints, and monitor the effectiveness of marketing campaigns.

In this article, we will look into all concepts connected with sentiment analysis topics, from understanding the basics of what it is, to how it can be used to gain an advantage, and improve customer service. As sentiment analysis continues to evolve and improve, it's becoming an increasingly valuable tool for businesses to stay ahead of the curve and stay in tune with their customers.


What is Sentiment Analysis?

Sentiment analysis is a subfield of natural language processing (NLP) that examines text to identify and extract subjective information from it. Its main goal is to classify the polarity of a text, i.e. whether it is positive, negative, or neutral. The polarity is often expressed as a numerical rating known as a “sentiment score”. It could be calculated for an entire text or just for an individual phrase. However, it goes beyond polarity by identifying specific feelings and emotions, urgency, and even intentions expressed in a text. Moreover, sentiment analysis techniques can be tailored to meet the specific needs of different industries and applications. 

How does Sentiment Analysis work

Before starting a sentiment analysis, as a first step, it's important to choose an approach that is suitable for your specific use case and data. The choice of approach will depend on several factors, such as the amount of data available, the complexity of the context, the desired level of accuracy, and the computational resources available.

There are 3 main approaches to sentiment analysis: 

Rule-based: uses a set of predefined rules and patterns to classify the sentiment of the text. This approach is simple and efficient, but it can be limited in its accuracy.

Automatic: uses machine learning-based or deep learning-based algorithms. This approach is efficient for large amounts of data, but it can be affected by the quality of the data and the complexity of the context.

Hybrid: approach is a combination of different methods, it can combine the advantages of multiple approaches to achieve better results.

Additionally, there is also a manual or human-based approach to sentiment analysis. This approach involves humans manually reading and analyzing text to determine the sentiment. This method is often used as a benchmark or as a second opinion when the automatic approach is used. 

Let us now delve deeper into each approach and gain a comprehensive understanding of its advantages and nuances.

Rule-based approach 

The rule-based approach to sentiment analysis is a method that utilizes a set of predefined rules and patterns to classify the sentiment of the text. This approach is commonly used in natural language processing (NLP) to identify and extract subjective information from text data.

The core of the rule-based approach is a set of linguistic rules and patterns that are used to identify sentiment in text. These rules can be based on a variety of linguistic features such as the presence of certain words or phrases, the use of certain grammatical structures, or even the sentiment of individual words. The rules are manually defined by experts in NLP, linguistics, or domain-specific experts.

Once the rules have been defined, the next step is to apply them to a given text. This is typically done using a program that tokenizes the text, breaking it down into individual words or phrases, and then applying the rules to each token. The program should also be able to handle different forms of text, such as tweets, reviews, or emails.

One of the advantages of the rule-based approach is that it allows for a high degree of control over the sentiment analysis process, as the rules can be tailored to the specific domain or use case. However, it also has its limitations, as it can be time-consuming to manually define rules, and also it can be affected by the complexity of the text and the context.

Despite its limitations, the rule-based approach is often used as a starting point for more advanced methods such as machine learning-based approaches, and it can also be used to improve the performance of these methods by incorporating domain-specific knowledge.

Automatic approach

The automatic approach to sentiment analysis is a method that utilizes machine learning techniques to classify the sentiment of the text. The process of sentiment analysis can be broken down into several steps, each building on the last to produce a comprehensive understanding of the data at hand:

Data collection: The initial step in sentiment analysis is gathering the data that will be put under the microscope. This data can come from a plethora of sources, such as social media platforms, customer reviews, or surveys. It's essential to ensure that the data is representative, diverse and unbiased. The more data, the more robust the analysis. And with the advent of big data and cloud computing, data collection is more accessible than ever before. So, whether you're a small business or a multinational corporation, you can start analyzing customer sentiment today.

Data pre-processing: The data collection process may yield a whole bunch of irrelevant information, typos, and even some dirty words, and that's where the pre-processing step comes in. It's like giving your data a spa day before sending it off for analysis. We scrub it clean, fix any typos, and make sure it's all polished and ready for the big show. This step is crucial for ensuring accurate results and making the most of the data you've collected. Think of it as a pre-game warm-up for your analysis, you can't just jump in without stretching first!

Feature extraction: It’s like a treasure hunt for sentiment analysis. We're digging through all the pre-processed data, searching for those golden nuggets of information that will help us understand the sentiment. We're looking for things like keywords and phrases that indicate positive or negative sentiment, emoticons that can give us a quick glimpse into how people are feeling, and even the overall sentiment of the text itself. Some other examples of features typically extracted from text data include bag-of-words, n-grams, and word embeddings. It's a crucial step in the sentiment analysis process and one that can make or break the accuracy of our results. After all, if we can't find the good stuff, we can't analyze it. Think of it as panning for gold, but with data.

Model training: Once the features have been extracted, a model can be trained on the data in order to learn how to identify sentiment. For this purpose, the chosen type of sentiment analysis and the appropriate algorithm is applied to the labeled data in order to learn how to identify sentiment. The choice of type and algorithm will depend on several factors such as the amount of data available, the complexity of the context, the desired level of accuracy, and the computational resources available.

Machine learning-based and deep learning-based approaches are commonly used for their accuracy and ability to handle large amounts of data. These methods involve training a model on labeled data, which is data that has been manually labeled as positive, negative, or neutral. Machine learning-based approaches use algorithms such as Naive Bayes, Support Vector Machines (SVMs), and Recurrent Neural Networks (RNNs) while deep learning-based methods use neural networks such as Convolutional Neural Networks (CNNs) and Long Short-term Memory (LSTM) networks.

For a more detailed understanding of sentiment, there's Graded Sentiment Analysis, which assigns a sentiment score to a piece of text, rather than just classifying it as positive, negative, or neutral. And for those in need of extracting sentiments about specific aspects, Aspect-based Sentiment Analysis is the way to go.

And for those looking for even more specialized insights, options such as Emotion detection, Opinion mining, and Intent detection offer a deeper understanding of the text.

Once you've chosen your type of sentiment analysis, it's time to choose the right algorithm. This will depend on factors such as the amount of data available, the complexity of the context, the desired level of accuracy, and the computational resources available. Algorithms such as Naive Bayes and SVMs are often used for smaller datasets, while more complex algorithms such as RNNs and LSTMs are used for larger datasets.

Model testing and evaluation: Once the model has been fine-tuned and polished, it's time to put it to the test. This is done by applying it to a set of unseen data, also known as the test set. This step is crucial as it allows us to measure the model's performance and identify any potential issues before deployment. Evaluation metrics such as precision, recall, and F1-score are commonly used to assess the model's accuracy in classifying the sentiment of the test data. Additionally, visualizations such as confusion matrices can also provide valuable insights into the model's performance, highlighting any areas of improvement. Ultimately, the goal of this step is to ensure that the model is reliable and robust enough for practical use.

Sentiment analysis: The final step is to put your model to the test by applying it to new, unseen data. This step is where all the hard work comes to fruition, as your model will classify the sentiment of the text, providing you with valuable insights and understanding of the opinions and emotions expressed within. It's important to keep in mind that this step should be done in a systematic manner so that you can be sure the results are reliable and can be used for further analysis. Additionally, it's important to validate the results with human evaluation to ensure that the performance of the model is at its best. This step is crucial to gain insights and making decisions based on the data.

One of the main advantages of the automatic approach is that it can handle large amounts of data and can also be more accurate than the rule-based approach, especially when dealing with more complex or nuanced text. However, it also has some limitations such as the need for a large amount of labeled data to train the model, and the difficulty of understanding the underlying reasoning of the model. It's also widely used in combination with a rule-based approach and other methods to improve the accuracy of the results.

Hybrid approach

The hybrid approach to sentiment analysis is a unique blend of rule-based and automatic methods, combining the best of both worlds. It starts by utilizing pre-defined rules to identify sentiment in text, similar to the rule-based approach. Then, the output of this step is fed into a machine learning model, similar to the automatic approach, which fine-tunes the sentiment classification based on the patterns and features it learned during training.

This approach offers the advantages of both rule-based and automatic approaches, such as the ability to handle large amounts of data and provide more accurate results, especially when dealing with complex or nuanced text. Additionally, it allows for the incorporation of domain-specific knowledge and control over the process. However, it also requires more computational power and resources. The hybrid approach is considered one of the most advanced and accurate methods for sentiment analysis and it's widely used in various industries such as customer service, marketing, and social media monitoring.

Benefits of Sentiment Analysis

The Power of Objectivity

With sentiment analysis, human bias is removed from the equation, providing a consistent, objective method of determining sentiment. This is particularly valuable in industries such as finance and politics, where emotions can greatly influence decision-making.

Mass Processing Mastery

Sentiment analysis algorithms can quickly process vast amounts of data, making them a powerful tool for analyzing customer feedback or social media mentions on a grand scale.

Time is of the Essence

Sentiment analysis automates the process of analyzing text, freeing up time and resources for more valuable activities such as strategy development and decision-making.

Uniform Criteria

Manual sentiment analysis can be influenced by personal experiences, thoughts, and beliefs, leading to inconsistent results. Sentiment analysis systems, however, apply the same criteria to all data, improving accuracy and providing more in-depth insights.

Real-Time Insight

Sentiment analysis allows for real-time analysis of critical issues, such as a potential public relations crisis on social media or a dissatisfied customer. This allows for immediate action to be taken, potentially mitigating negative consequences.

Sentiment analysis in action 

Sentiment analysis is a versatile tool with a wide range of applications across various industries. From finance to retail, hospitality to technology, businesses are finding new ways to leverage the power of sentiment analysis to gain valuable insights and improve their operations. Whether it's tracking customer sentiment on social media, analyzing product reviews, or gauging the effectiveness of marketing campaigns, sentiment analysis is quickly becoming a go-to tool for businesses looking to stay ahead of the competition. Below, is the list of the interesting use cases of Sentiment Analysis:

Sentiment Analysis in the Lab

Sentiment analysis plays a crucial role in modern science, allowing researchers to gain insight into the effectiveness of their experiments and detect any potential issues before they become major problems.

As an example, sentiment analysis is being used by hospitals to gather patient feedback on social media to improve healthcare facilities. By analyzing over 150,000 tweets, researchers found that patients were most satisfied with their treatment during the COVID-19 pandemic, with 52.6% of tweets being reasonable compared to 24.3% negative. Through natural language processing and polarity and subjectivity distribution, sentiment analysis helps medical professionals make better decisions for the routine management of cancer patients.

Product Review Monitoring

With the rise of e-commerce, customers have more options than ever before when it comes to shopping for products. And with that comes a wealth of product reviews available online, from websites like Amazon to social media platforms like Instagram and TikTok.

Product review monitoring allows businesses to gain insights into how customers feel about their products and detect any issues in real-time before they spiral out of control. Analyze customer feedback from various sources and gain a deeper understanding of customer sentiment beyond just the number of reviews or the average rating.

Take, for example, a new line of smartwatches that are being released on the market. Product review monitoring can be used to track customer sentiment on the new product, identify any potential issues with the product such as battery life or connectivity, and nip them in the bud before they escalate into significant issues. This can help improve customer satisfaction and boost sales for the company. With sentiment analysis, businesses can stay ahead of the competition and ensure customer satisfaction by constantly monitoring and improving their products.

Crisis Management with Sentiment Analysis

As the world becomes more digital, crisis management is no longer just about putting out physical fires. It's about managing public perception and controlling the narrative in the digital sphere. And that's where sentiment analysis comes in. It's the ultimate tool for understanding public opinion and gauging the effectiveness of your crisis response in real time.

In the event of a major oil spill in the gas and oil industry, sentiment analysis can be used to monitor public opinion and track the spread of negative sentiment across social media and news outlets. This allows the company to quickly identify and address any misinformation, as well as save the brand’s reputation.

Content Creation:

Sentiment analysis is a vital tool for creating content that resonates with your audience. By monitoring the chatter around your brand, you can identify trending topics, popular formats, and what type of content is resonating with your audience. This information can be used to create content that is tailored to your audience's interests and preferences.

One popular YouTube channel that has used sentiment analysis is PewDiePie. The channel, which is run by Felix Kjellberg, has used sentiment analysis to track and understand the sentiment of his audience towards his videos and content. This allows him to better understand what his audience likes and dislikes, and create content that aligns with their preferences. Additionally, PewDiePie also uses sentiment analysis to track and respond to comments on his videos, allowing him to better engage with his audience and build a stronger community.

Challenges of Sentiment Analysis

As with any technology, sentiment analysis isn't without its challenges. Language is a tricky beast and Sentiment Analysis has to deal with its nuances. From the ever-elusive sarcasm to the sneaky negation, these roadblocks can trip up even the most advanced systems. But fear not, for with a little understanding and some clever workarounds, these obstacles can be overcome. Let’s take a look at the most tricky challenges of sentiment analysis:

Irony and Sarcasm

Irony and sarcasm are often considered the kryptonite of sentiment analysis. These forms of language use can be incredibly difficult for machines to understand, as they rely on context and tone to convey meaning. For example, if someone says "I love this weather, it's so hot and sunny," the use of "love" and "hot and sunny" together is ironic because these are typically negative words. Similarly, if someone says "Wow, that was a great presentation, I learned so much" with a heavy dose of sarcasm, it's clear that the person did not find the presentation to be good. These examples illustrate why irony and sarcasm can be so challenging for sentiment analysis algorithms to detect, as they often require a deep understanding of the speaker's intent, tone, and context.


It's a tricky one, ain't it? It's like trying to understand a riddle wrapped in a mystery inside an enigma. Sentences that can be interpreted in multiple ways can be a real headache for sentiment analysis systems. For example, "I'm so happy I could cry" could be interpreted as genuine happiness or extreme sarcasm. And let's not even get started on "I'm fine", which can mean anything from "I'm great" to "I'm about to jump off a bridge". Ambiguity is a real challenge for Sentiment Analysis, and it's not for the faint of heart. But hey, where's the fun in easy challenges? Let's embrace the ambiguity and make SA systems smarter.

Idiomatic expressions

These are the spice of language, adding flavor and flair to our communication. But they can also be a real headache for sentiment analysis systems, as they often have a figurative meaning that's not immediately obvious. For example, when someone says "I'm feeling under the weather," they're not literally talking about the weather, but rather expressing that they're feeling ill. These types of phrases can be tricky for sentiment analysis systems to understand, as they require a deep understanding of language and context to accurately interpret. But hey, that's why we have NLP experts to help us navigate these choppy waters. So let's raise a glass to the idiomatic expressions, the little curveballs that keep our language interesting and our sentiment analysis systems on their toes.


It can be a tricky concept for sentiment analysis systems to grasp. Imagine a sentence like "I don't hate this product" - to the human reader, it's clear that the sentiment expressed is not negative. But to a machine, "hate" and "don't" can be confusing without proper context. This is why understanding negation is crucial for accurate sentiment analysis, and it's a challenge that researchers and developers are constantly working to overcome.


Emojis and emoticons are often used to convey emotion in text, but interpreting them can be tricky for sentiment analysis systems. These little pictures can have different meanings depending on the context, and even the same emoji can have a different connotation depending on who is using it. For example, a smiling face emoji from a friend might indicate happiness, but the same emoji from a customer service representative might indicate insincerity. As such, sentiment analysis systems need to be trained to understand the nuances of emojis and emoticons in order to accurately interpret the sentiment behind a message.

How to start with Sentiment Analysis?

In today's digital landscape, finding solutions for any task is as easy as a few clicks. The same can be said for sentiment analysis, with a plethora of ready-made solutions readily available on the market. Rather than reinventing the wheel and starting from scratch, using the advancements in technology by utilizing a product-ready tool seems like the logical choice, especially when time is a critical factor.

To get started and become familiar with the sentiment analysis process, an NLP-as-a-Service platform like OneAI is a great solution. This platform offers pre-trained language skills, such as sentiment analysis, through its user-friendly APIs. It's a great way to quickly and efficiently gain valuable insights into public opinion. 

Let’s put OneAI to test and see how we can get emotions from an unhappy client’s letter. Please, follow me to OneAI's Language Studio to run the analysis. 

We can see how the platform looks in the screenshot below:

Underneath the pipeline box, you can see Language Skills, which offers a variety of options for applying AI to your content. Among the many options available, we'll be focusing specifically on sentiment analysis for this demonstration.

To begin, simply paste your e-mail to the text input section. To extract the sentiments, all you have to do is drag the "Emotions" skill into the pipeline box and hit "run." In mere moments, you'll have your results ready illustrated in the screenshot below:

Let’s take a moment and check the results closely. As represented in the screenshot there are some clearly negative statements here:

However, as we know from this article, sarcasm and irony can be difficult for NLP systems to accurately identify. But, OneAI's advanced capabilities have successfully tagged these nuanced statements with precision. The platform's ability to detect and understand the use of contradictory statements within a single sentence is particularly noteworthy.

These results can already be used in your project by just copying the code from the platform to your code editor. For more details, check these multiple tutorials:

Quickly Summarize and Understand Emails

Summarize and Understand Meetings With Ease

Generate Automatic Product Meeting Summaries

Generate Video Highlights


Sentiment analysis is a powerful tool for businesses and organizations to gain insights into the public's perception of their brand, products, and services. However, as with any cutting-edge technology, there are certain challenges to overcome. But with advancements in natural language processing and machine learning, we can expect sentiment analysis to become even more sophisticated and accurate in the future. As more and more data is generated by social media, chatbots, and other digital channels, the ability to analyze and understand the sentiment in real time will become increasingly important for businesses looking to stay ahead of the curve.

And for those who are looking to take your sentiment analysis game to the next level, give OneAI a try and see the difference it can make for your brand.

Master Sentiment Analysis Now!

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