ELI5: Explain Like I'm 5

Minimum mean-square error

When we have some data that we want to analyze or make predictions about, we typically use a model to help us understand how the data behaves. A model is just a simplified representation of the real world that can help us make predictions or draw conclusions.

Now, when we use a model we typically want to make sure that our predictions or conclusions are as accurate as possible. One way to measure how accurate the model is, is by calculating the difference between the model's predictions and the actual values of the data. This difference is called an "error".

So, in order to make our model as accurate as possible, we want to minimize the amount of error that the model makes. One popular technique for doing this is called "minimum mean-square error".

This is just a fancy way of saying that we want to choose the parameters of our model, or the way we build our model in a way that makes the average error as small as possible. We call this average error the "mean-square error".

The "mean-square error" is just the average of the squared errors across all data points. Squaring the errors helps to make sure that we are penalizing larger errors more heavily than smaller errors. This is important because we care more about large errors than we do about small errors when we are trying to make our model as accurate as possible.

So, in short, when we use the technique of minimum mean-square error, we are trying to find the best parameters for our model that make the average (mean) of the squared (square) errors as small as possible. This helps us create models that are more accurate and that can help us make better predictions and conclusions about our data.