ELI5: Explain Like I'm 5

Full information maximum likelihood

Full information maximum likelihood (FIML) is a method that helps us estimate the values of unknown things (variables) when we have lots of information (data) about them. Imagine you have a big puzzle with many pieces. FIML is like a special tool that helps us put all the pieces of the puzzle together in the best way possible.

When we collect data, we usually get information about many different variables. These variables might be related to each other in some way. FIML helps us figure out how the variables depend on each other.

Imagine you have a big table with numbers, and each row represents different people. The columns represent different things about these people, like their age, height, and weight. FIML helps us find out how these different things are related to each other. For example, FIML can help us figure out if taller people tend to be heavier or if older people tend to be taller.

The first step in using FIML is to come up with a model. Think of a model as a set of rules or equations that describe how the variables are related. These rules are based on our understanding of the world and what we already know. For example, we might think that age and height are related in a certain way based on what we have observed before.

Once we have a model, we use FIML to estimate the values of the unknown variables. FIML looks at the data we have and tries to find the values of the variables that make the model fit the data the best. It does this by considering all the information we have, not just one piece at a time. It tries to find the values that make all the numbers in the table fit together in the best way possible.

FIML uses a technique called maximum likelihood to make these estimates. Maximum likelihood is like a detective trying to find the best explanation for a crime. FIML looks at all the evidence (data) and tries to find the values of the variables that make the data the most likely to be true based on our model.

To do this, FIML looks at the patterns in the data and tries to find the values of the variables that make these patterns the most likely. It calculates the likelihood of each possible set of values and picks the one that has the highest likelihood.

In summary, FIML is a tool that helps us estimate the values of unknown variables by looking at lots of data and finding the values that make the data fit together the best based on a model. It does this by using a technique called maximum likelihood, which tries to find the values that make the data the most likely to be true.