Top 10 Data Science Formulas You Must Know

Whether you're just starting out or brushing up on the essentials, mastering these 10 core formulas will help you speak the true language of data.

In this post, we break down the Top 10 Formulas every data scientist or analyst should know — explained in plain text, simple terms, and practical context.

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🧠 Why These 10 Formulas?

These formulas form the foundation of everything in Data Science — from statistics to machine learning and beyond. They help you:

• Understand your data

• Discover patterns

• Make predictions

• Communicate insights

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📘 The Top 10 Formulas (with Plain Text Format)

1. Mean (Average)

Mean = Sum of all values / Number of values

2. Median

If dataset is odd:
Median = Middle value after sorting
If dataset is even:
Median = (n/2-th value + (n/2 + 1)-th value) / 2

3. Mode

Mode = Most frequently occurring value in the dataset

4. Standard Deviation (σ)

σ = sqrt( Σ (xᵢ - μ)² / N )
→ Measures how spread out the values are from the mean.

5. Variance (σ²)

σ² = Σ (xᵢ - μ)² / N
→ It’s the square of standard deviation.

6. Correlation Coefficient (r)

r = Σ[(xᵢ - x̄)(yᵢ - ȳ)] / √(Σ(xᵢ - x̄)² * Σ(yᵢ - ȳ)²)
→ Measures strength and direction of linear relationship.

7. Logistic Function (Sigmoid)

P = 1 / (1 + e⁻(β₀ + β₁x))
→ Used in logistic regression to predict probabilities.

8. Euclidean Distance

Distance = √[(x₂ - x₁)² + (y₂ - y₁)²]
→ Used in clustering, k-NN, etc.

9. Cosine Similarity

cos(θ) = A · B / (||A|| ||B||)
→ Measures similarity between two vectors.

10. Probability Formula

P(E) = Number of favorable outcomes / Total number of outcomes

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📊 What You Get in This Post

• ✅ Easy-to-read plain text for each formula

• ✅ Real-world examples and relevance

• ✅ Quick reference for beginners & pros

• ✅ Visual summary (see banner image above ☝️)

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📎 Bookmark This!

This post is part of Uplatz’s “Formula Series”, where we cover 10 key formulas from fields like:

• 🔐 Cybersecurity

• 📈 Machine Learning

• 🧪 Data Analytics

• 💼 Business Intelligence

Follow us to catch the next batch!