How to Use Our Calculators

Step-by-step guides to get the most out of StatLearn

Quick Navigation

1
Normal Distribution Calculator
2
Probability Calculator
3
Histogram Builder
4
Data Explorer & Outlier Detector

Normal Distribution Calculator

Learn to calculate probabilities and z-scores

Open Calculator

What is it for?

The Normal Distribution Calculator helps you find probabilities, z-scores, and percentiles for normally distributed data like test scores, heights, and IQ scores.

Step-by-Step Guide

  1. 1
    Enter the Mean (μ)

    This is the average value of your distribution. For IQ scores, it's 100.

  2. 2
    Enter the Standard Deviation (σ)

    This measures the spread. For IQ scores, it's 15.

  3. 3
    Choose Your Mode
    • X → P: Find the probability for a given value
    • P → X: Find the value for a given probability
    • Between: Find probability between two values
  4. 4
    View Results

    See the z-score, probability, and percentile instantly, along with an interactive visualization.

💡 Example Use Case

"If the average test score is 75 with a standard deviation of 10, what percentage of students scored below 85?" Set mean=75, SD=10, x-value=85, and choose X→P mode. The result shows 84.13% of students scored below 85.

Probability Calculator

Master combinations, permutations, and more

Open Calculator

What is it for?

Calculate probabilities for combinations, permutations, binomial events, and conditional probability. Perfect for lottery odds, committee selection, and probability problems.

Key Features

Combinations (nCr)

When order doesn't matter. Example: Choosing 3 people from 10 for a committee.

Permutations (nPr)

When order matters. Example: First, second, and third place winners.

Binomial Probability

Repeated independent trials. Example: Probability of 7 heads in 10 coin flips.

Conditional Probability

Probability given another event occurred. Uses Bayes' theorem.

🎲 Quick Tip

Order matters? Use permutations. Order doesn't matter? Use combinations. For example: Choosing lottery numbers = combinations. Race finishing positions = permutations.

Histogram Builder

Visualize your data distribution

Open Calculator

Step-by-Step Guide

  1. 1
    Enter Your Data

    Type numbers separated by commas, spaces, or new lines. Or upload a CSV file.

  2. 2
    Adjust Bins

    Use the slider to change the number of bins. The calculator suggests an optimal value.

  3. 3
    View Statistics

    See mean, median, mode, standard deviation, and more.

  4. 4
    Export

    Download your histogram as a PNG image for reports or presentations.

📊 Data Tips

  • • Need sample data? Click "Load Example" to see how it works
  • • Toggle the normal curve overlay to compare your data to a normal distribution
  • • Use the frequency table below the chart for exact values

Data Explorer & Outlier Detector

Analyze datasets and find outliers

Open Calculator

Outlier Detection Methods

IQR Method (Interquartile Range)

Values below Q1 - 1.5×IQR or above Q3 + 1.5×IQR are outliers. Best for skewed distributions.

Z-Score Method

Values with |z-score| > 3 are outliers. Works well for normal distributions.

Modified Z-Score (MAD)

Uses median absolute deviation. More robust to extreme outliers than standard z-score.

⚠️ Important

Not all outliers are errors! Before removing outliers, consider if they represent real data or measurement errors. The tool shows you a "before and after" comparison to help you decide.

General Tips for All Calculators

🔗 Share Your Results

Every calculator has a "Share" button that creates a unique URL with your inputs. Share it with classmates or save it for later.

📚 View History

Your calculation history is saved in your browser. Click the history icon to see past calculations and restore them.

🎨 Interactive Visuals

Many visualizations are interactive. Try dragging sliders, clicking on chart elements, or hovering for more details.

🔒 Privacy First

All calculations happen in your browser. Your data never leaves your device, ensuring complete privacy.