✅ Statistics & Probability Cheatsheet 📚🧠

📌 Descriptive Statistics:
⦁  Mean = (Σx) / n
⦁  Median = Middle value
⦁  Mode = Most frequent value
⦁  Variance (σ²) = Σ(x - μ)² / n
⦁  Std Dev (σ) = √Variance
⦁  Range = Max - Min
⦁  IQR = Q3 - Q1

📌 Probability Basics:
⦁  P(A) = Outcomes A / Total Outcomes
⦁  P(A ∩ B) = P(A) × P(B) (if independent)
⦁  P(A ∪ B) = P(A) + P(B) - P(A ∩ B)
⦁  Conditional: P(A|B) = P(A ∩ B) / P(B)
⦁  Bayes’ Theorem: P(A|B) = [P(B|A) × P(A)] / P(B)

📌 Common Distributions:
⦁  Binomial (fixed trials)
⦁  Normal (bell curve)
⦁  Poisson (rare events over time)
⦁  Uniform (equal probability)

📌 Inferential Stats:
⦁  Z-score = (x - μ) / σ
⦁  Central Limit Theorem: sampling dist ≈ Normal
⦁  Confidence Interval: CI = x‌ ± z*(σ/√n)

📌 Hypothesis Testing:
⦁  H₀ = No effect; H₁ = Effect present
⦁  p-value < α → Reject H₀
⦁  Tests: t-test (small samples), z-test (known σ), chi-square (categorical data)

📌 Correlation:
⦁  Pearson: linear relation (–1 to 1)
⦁  Spearman: rank-based correlation

🧪 Tools to Practice: 
Python packages: scipy.stats, statsmodels, pandas 
Visualization: seaborn, matplotlib

💡 Quick tip: Use these formulas to crush interviews and build solid ML foundations!

💬 Tap ❤️ for more