How to Reduce the Similarity Index in Plagiarism?

Some plagiarism checkers tools like Turnitin have a similarity index in their plagiarism detection that suggests that the input text likely contains plagiarism.

A higher similarity score usually means the input text matches existing text (available on the web or in the tool’s database) more than enough, suggesting a higher chance of it containing plagiarism.

However, a high similarity score doesn’t flatly equate to plagiarism. It doesn’t necessarily mean that the input text is a tweaked version of existing materials. It is because a similarity score can occur naturally if your text matches existing materials, which can happen even if the text is entirely written by you. However, plagiarism detection tools with a high similarity score can flag the entry document for further examination, which begs the question: How do we get rid of similarity index?

In this article, we will explore effective techniques that can help us reduce the similarity index of AI plagiarism detection tools.

What Causes the Similarity Index

Before we skip to the techniques, we need to understand what causes the similarity index. Similarity indexes are triggered by exact or close matching of the text with existing publications, which includes academic papers and websites. Tools like Turnitin also check similarity against students’ assignments stored in its database.

Similarity index can be triggered even if your paper cites the sources properly, if they are identical to the sources, which, again, does not equate to plagiarism. So, if your concern is strict plagiarism only, you can ignore the similarity score, otherwise you can various techniques to reduce it:

Techniques to Reduce the Similarity Index

Similarity indexes can be reduced through a number of simple techniques, including paraphrasing and summarizing: 

Paraphrasing Techniques

Paraphrasing means rewriting text to make it different from the original one without losing the meaning. It is the most powerful method to reduce the similarity index. But to be effective, you need to do more than just replacing words with synonyms.

1. Change Sentence Structures:
   One of the techniques used to paraphrase text is changing sentence structures. This involves splitting longer sentences into smaller sentences and combining smaller sentences into longer sentences.
   
   If you find it challenging to restructure sentences, Paraphraser.us — an AI paraphrasing tool — can help you restructure sentences easily. Just input your text into the tool and click the “Paraphrase” button, the tool will paraphrase your input text and display the output for you to copy.
   
   Protip: Before you start paraphrasing, make sure you understand the meaning of the original text thoroughly to avoid contextual and meaning mistakes.
   
   

2. Use Synonyms:
   Another effective paraphrasing technique is replacing words with their synonyms. When replacing words, make sure the synonyms carry the same meaning as the original word. A lot of times, words, despite being synonyms, can have nuances in their meanings, making them unsuitable for replacement. Poor synonymizing can lead to change in the meaning of the text.

3. Switch Between Voices:
   Another effective way to paraphrase text is by changing between sentence voices. You can do this by changing sentences written in active voices to passive voices and passive voices to active voices.  For example, let’s say the sentence “Global warming is caused by human activities such as burning fossil fuels.” contributes to the similarity index. You can change this sentence into “Human activities such as burning fossil fuels cause global warming.”
   
   Changing the voice of a sentence can completely reshape it and make it distinct from the original one, allowing you to reduce similarity score without drastic changes.

Summarize Where Possible

Another way to lower the similarity index is by summarizing larger sections of content. For example, if you are referring to a detailed study or report in your assignment, instead of rewriting it paragraph by paragraph, consider summarizing it by condensing the ideas in one or two original sentences.

Summarizing texts helps make it more original and concise.

Cite Properly

Citations are a must-do in academic writing. This means if you are a student writing assignments, be it an essay or a thesis, you must always cite your sources, even if you paraphrase or summarize the source text.

Although citing the sources does not decrease the text’s similarity score, it is required for academic code of conduct and ethical reasons. Leaving out citations means risking your academic integrity and possibly falling into a legal jeopardy.

Always make sure to cite the original source properly, ensure there are no errors in the citation elements; work titles, author names, dates, etc., and remember to follow your required style guide; CMoS, MLA, or APA.

With sources cited and proper credit given, you can ignore much of the similarity score and focus on writing without worrying about potential plagiarism.

Common Mistakes to Avoid

In addition to the techniques to reduce similarity score, you must avoid the following common mistakes for optimal results:

1. Using Synonyms Without Understanding:
   Do not try to change every word in the text for its synonym. Many words don't have synonyms with the exact meanings, so they may be used as they are. For instance, turning “global warming” into “planet heating” may confuse the reader or sound unnatural.
   
   

2. Paraphrasing Without Changing Structure:
   Sentence structure plays a crucial role in the shape of a text. But changing only some words here and there, without reworking the sentence structures, can result in loose or poor paraphrasing, which more or less retains the original shape of the text.
   
   Changing only a few words but keeping the same sentence structure still counts as close similarity. AI plagiarism tools can pick up on repeated phrasing even when some vocabulary is changed.
   
   

3. Deleting Content Blindly:
   Do not delete content just because it is showing similarity. Deleting entire blocks of content just for the sake of similarity can reduce the quality of text and even weaken or deform the argument. Instead of deleting, paraphrase the content to make it distinct and try to reduce the similarity score manually.
   
   

4. Over-Quoting:
   Quotation marks (“”) are used when you write a source’s text verbatim (i.e., as it is originally). These indicate that the quoted text is not the author’s words, but are taken from elsewhere, usually followed by the citation of the source.
   
   However, too much quoting can give rise to the similarity index and lead to a high score, because, obviously, you are copying a source text directly. So, if you want to lower the score, make sure you are not overdoing direct quotations — use them only where necessary.

5. Forgetting to Cite Paraphrased Ideas:
   Even when paraphrased, if an idea or piece of writing or speech belongs to someone else, you have to cite that source. Otherwise, not citing a paraphrased or summarized text can lead to plagiarism.

Avoiding these mistakes keeps your writing both original and meaningful. It also helps you strike the right balance between originality and clarity.

Conclusion

Similarity index refers to how identical your text is to existing publications online. Some plagiarism checker tools like Turnitin feature similarity index or score to measure how likely it is that the input text contains plagiarism. However, various techniques, as explained in this article, ensure your work is not just original but also help you reduce the similarity index if you run into this problem. These techniques include paraphrasing practices, such as restructuring sentences, synonymizing, and switching between voices, summarizing, and ensuring proper citations.