What is Regression Line – Formula, Calculation, Example, Application

# What is Regression Line – Formula, Calculation, Example, Application

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Atul Harsha
Senior Manager Content
Updated on Oct 12, 2023 09:28 IST

The regression line represents the best estimate of one variable based on the value of another, capturing the average relationship between them. In simple terms, the regression line is like a guide that shows us the general trend between two things.

Imagine you’ve just launched a brand-new type of sneaker on an online store. Every day, you run ads on social media platforms like Instagram and YouTube to promote your sneakers. You’ve noticed something interesting: The trend was – the more ads you run, the more sneakers you sell!

## Introducing the Idea of a Trend

Think about it like this: the more often people see something, the more likely they are to buy it, right? So, if we were to draw this on a graph, with the number of ads on the bottom (X-axis) and the number of sneakers sold on the side (Y-axis), we’d see a line going up. This line which shows us the relationship between the number of ads and sales is the regression line.

## What is a Regression Line?

A regression line or line of regression is a straight line that best represents the relationship between two sets of data. By understanding this relationship, businesses and researchers can make better decisions and forecasts.

For example, on an e-platform selling sneakers, if we chart the number of online ads against the number of sneakers sold, the regression line will indicate how, on average, sales might increase with each additional ad. It’s like drawing a line of best fit through our data points to predict how many sneakers we might sell based on our advertising efforts.

## Drawing the Regression Line

On a graph paper or whiteboard, draw a scatter plot with some points representing the number of ads and the number of sneakers sold. Then draw a line that seems to fit the points best.

This line is our magic predictor! It helps us guess “How many sneakers we might sell if we run a certain number of ads.

Read More: How to perform Regression Analysis?

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## Why use Regression Line?

Using a regression line provides clarity, direction, and a data-driven approach to various challenges and questions across different fields. It helps with the following:

• Predictive Insights: Helps forecast future values based on historical data.
• Decision Making: Assists businesses in making informed decisions, such as budget allocation or inventory planning.
• Understanding Relationships: Reveals the nature and strength of the relationship between variables.
• Optimizing Strategies: Enables fine-tuning of strategies, like marketing campaigns, based on predicted outcomes.
• Resource Allocation: Guides where resources (like money or time) can be most effectively spent.
• Risk Management: Helps in assessing risks and uncertainties in various scenarios.
• Cost Efficiency: By predicting outcomes, businesses can avoid unnecessary expenses.
• Performance Evaluation: Allows for the assessment of the effectiveness of interventions or changes made in a system.

## Introducing the Formula

The line can be described with a simple formula:

### Sneakers Sold = (Number of ads × Sales boost) + Base Sales

• Sales boost is how much our sales increase for each ad, on average.
• Base Sales are the sales we make even without any ads, maybe from people who just stumble upon our website.

### Simple Calculation Example:

Let’s say for every ad we run, we sell 5 more sneakers, and we have a base sale of 10 sneakers even without ads. If we run 20 ads today, how many sneakers can we expect to sell?

Using the formula: Sneakers Sold = (20 ads × 5 sneakers/ad) + 10 sneakers = 110 sneakers.

So, by running 20 ads, we can predict we’ll sell 110 sneakers!

Read More: Understanding and implementing Linear Regression formula in depth

### Making it Exciting:

Now, here’s the thrilling part: Imagine if we could perfectly predict our sales just by deciding how many ads to run! We could plan special offers, stock up our inventory, and even set goals for our business. This prediction line, or regression line as the experts call it, is like having a crystal ball for our sneaker business!

### Guess the Sales! Game:

Before we dive deeper, let’s play a quick game. Here are three days where we ran 10, 15, and 25 ads respectively. Based on our previous discussion, can you guess how many sneakers we sold on each of those days? Write down your predictions!

Learn More: Compare and get certified with best Regression Course in the market

## Real-World Implications

• Budgeting and Planning: Knowing how ads affect sales isn’t just cool—it’s crucial for our business. If we know that every ad brings in sales of 5 sneakers, and each sneaker gives us a profit of \$10, then we can calculate how much profit we’ll make for each ad. This helps us decide our advertising budget. Too few ads, and we miss out on sales. Too many, and we might be wasting money.
• Stock Management: Imagine the chaos if 500 people ordered our sneakers, but we only had 100 in stock! Or the opposite, where we stock up 500 sneakers, but only 10 get sold. Using our regression line, we can predict sales and manage our stock better.

## Historical Origin of Regression

The term ‘regression’ originated from Sir Francis Galton’s study on heredity. While examining the heights of parents and their children, he observed that although children of tall parents tended to be tall themselves, their heights often “regressed” towards the average height of the population. Thus, he named this phenomenon “regression to the mean.”

## Conclusion with a Thought-Provoking Question

Regression helps us make informed decisions, but it’s also essential to stay flexible and adapt to changes. With the power of prediction, we can plan, strategize, and grow our business. It lets us peek into the future and make smart decisions today. Whether it’s sneakers, concert tickets, or even ice creams on a hot day, understanding trends can be a game-changer!” But here’s a question for you: If you had this predictive power, how would you use it in your daily life or future business?

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