When data follows a normal distribution, the bell curve is a graph that depicts how it is spread out. The name comes from the fact that it appears like a bell. The midpoint of the curve is the highest point, which is the most common value. The two sides of the curve show values that are not as prevalent.
The bell curve is a common tool in finance for looking at data and guessing how the market will act. If you're new to the stock market, words like "normal distribution" and "standard deviation" could sound hard to understand. Don't worry, though; this guide breaks down the bell curve into simple terms so you can see how it works and how it can help you with money.
What is the Bell Curve?
A bell curve is a type of graph that shows how likely something is to happen. The middle half is high, and both sides slope down the same amount, thus it looks like a hill or a bell. The curve's key feature is that it is symmetrical.
The highest point in the middle shows the most common or average event in the data collection. The sides show things that happen less often. If you measure the height of pupils in a class, most of them will be around the average height, which is the highest point. At the extremes of the curve, you will see a few pupils that are extraordinarily tall or very short.
The standard deviation is another crucial part of the bell curve. It shows us how spread out the data is. If the bell curve is narrow, it suggests that the data points are close to the average. If the curve is larger, it means that the data points are more spread apart.
How to Use Bell Curve in Finance?
The bell curve is an incredibly helpful tool in finance when it comes to trend analysis and forecasting. Below are a few of the common applications for it.
Determining Likelihoods
Investors utilise the bell curve to assess probabilities of various outcomes happening, such as the possible price of a stock or bond in the future.
Evaluating Data
The bell curve provides clarity regarding the distribution of data. This clarity allows for easier detection of patterns, trends, and outliers in the data.
Making guesses
The bell curve can help you guess what might happen when data is normally distributed. It can demonstrate, for example, how likely it is that a stock will go up or down within a specific range.
Looking at two sets of data
It's straightforward to compare two datasets when they both follow a bell curve. Investors can easily see whether one stock or investment acts differently than another.
Example of a Bell Curve
Consider that you are looking at the test scores of 1,000 students. The data suggests that most students got approximately 70 marks when it was shown on a graph. A lesser fraction of pupils get scores that are very high (above 90) or very low (below 50). The graph makes a bell-shaped curve when you join the dots.
The same goes for money. Let's say that a stock's average daily return is 1%. The return will usually be close to this value. Some days it might be higher or lower, but it doesn't happen very often. Investors can observe this distribution plainly thanks to the bell curve. This makes it easier to figure out hazards and come up with plans.
Bell Curve and Other Non-Normal Distributions
It is important to note that while bell-curved data is easy to understand because it is symmetric and the data is centred around the mean, not all data is, nor does it necessarily need to be, normally distributed in real-life conditions. For instance, speculating what prices would do in response to certain news or events may lead to a lot of uncertainty, as the bell curve in reality may or may not effectively respond in a normal fashion.
Distributions that are not normal often share a characteristic known as "fat tails." "Fat tails" means that extremely high (and low) events will happen more frequently than the bell curve would have suggested. Investors track these tails because they represent catastrophic risks, such as the impending market crash.
Characteristics of the Bell Curve
Here are the essential parts of the bell curve that can help us comprehend it better:
Around 68% of the data is within one standard deviation.
Approximately 95% of the data is contained within 2 standard deviations.
Three standard deviations cover about 99.7% of the data.
This is why the bell curve is such a useful way to figure out probabilities.
Advantages of the Bell Curve
There are several good things about the bell curve when it comes to finance and data analysis:
Easy and Clear - The bell curve makes it easy to observe how data is spread out.
Helps with figuring out probabilities - Investors can rapidly figure out how likely it is that something will happen within a certain range.
Good for Making Predictions - The bell curve lets us make credible predictions about what will happen in the future when the data is regularly distributed.
Tool for Comparison - It makes it easier to compare two or more datasets, which helps investors find differences in risks or trends.
Used and understood by many - The bell curve is a prevalent idea in business, education, and science, which makes it easier to use in many areas.
Limitations of the Bell Curve
The bell curve is helpful, but it has some big problems:
Only Works with Normal Data - The bell curve only works with data that is regularly distributed. A lot of financial datasets aren't normal, which makes the curve less credible.
Thinks About Symmetry - In the real world, data is not always exactly symmetrical. Data might be biassed by sudden events or shocks.
Not Good for All Types of Data - The stock market is very unstable. A bell curve doesn't do a good job of explaining the big swings that stocks and other instruments typically make.
Investors frequently utilise the bell curve together with other tools to help them make judgements because of these restrictions.
Conclusion
The bell curve is a simple yet powerful approach to show how data is spread out. It is often used in finance to figure out probabilities, look for patterns, and compare datasets. Its key strength is that it is symmetrical and can plainly represent averages.
But it shouldn't be used by itself. The bell curve can't fully explain why financial markets typically have non-normal distributions. Extreme events, wide tails, and volatility are all things that go beyond the curve.
Using the bell curve with other tools is the best way for investors to go about things. This will help them gain a better picture of the market. The bell curve can help you with your money matters once you realise what it can and can't do.
Additional Read: What is Demat Account