What is TF-IDF?
TF-IDF stands for Term Frequency-Inverse Document Frequency, and it's a statistical measure used in text analysis and information retrieval to evaluate how important a word is to a document in a collection of documents. The goal of TF-IDF is to identify the most relevant words in a document, in order to represent its content.
The term frequency (TF) is the number of times a term (word) appears in a document, normalized by the number of words in that document. The inverse document frequency (IDF) is a measure of how much information a term provides, which is calculated as the logarithm of the ratio of the total number of documents in a collection to the number of documents containing the term.
The product of the TF and IDF is used to calculate the weight of a term in a document, and the resulting weights can be used to rank the importance of terms in a document and across a collection of documents. The higher the TF-IDF weight, the more important the term is in the document, and the more it contributes to the document's representation.
TF-IDF is widely used in natural language processing and information retrieval tasks, such as text classification, clustering, and retrieval, and is a commonly used feature in machine learning algorithms for these tasks.
This calculator will take the math numbers from your favorite TF-IDF tool and tell you the number of instances you need add in order to meet the max TF-IDF based on your competitions usage. Its made to support the output of SEO Powersuite's WebSite Auditor software, but any SEO tool that provides you the scores will work as well.
It's worth noting that this is just an estimate, and the exact number of instances you need to add may vary depending on the distribution of other terms in your content. Additionally, it's important to consider whether adding more instances of the keyword will make the content appear unnatural or spammy, which can negatively impact the reader experience.
What is the TF-IDF Formula?
The formula for computing the TF-IDF weight of a term in a document is as follows:
TF(t, d) = (number of times term t appears in document d) / (total number of terms in document d)
IDF(t, D) = log((total number of documents in collection D) / (number of documents containing term t))
TF-IDF(t, d, D) = TF(t, d) * IDF(t, D)
t is the term for which the TF-IDF weight is being calculated.
d is the document in which the term appears.
D is the collection of documents.
The logarithm used in the formula for the IDF can be with any base, although common bases used are base 2 and base 10. The choice of base can affect the resulting values of the TF-IDF weights, but it doesn't affect the ranking of the terms in a document or collection of documents.