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Crash course in stats for Machine Learning

You are not required to be aware of statistics prior to starting your learning journey, and application of machine learning. You can begin today. 

Nonetheless, being aware of some statistics can be very beneficial to comprehend the language leveraged in machine learning. Being aware of some statistics will ultimately be needed when you wish to begin making strong claims about your outcomes. 

In this blog article you will find out a few critical concepts from statistics that will provide you the confidence you require to begin and make progress within machine learning. 

Statistical inference 

There are procedures in the physical world that we would wish to comprehend.  

For instance, human behaviours like clicking on and add or purchase a product. 

They are not direct to understand. There are intricacies and uncertainties: The procedure has an aspect of randomness to it (it is stochastic) 

We comprehend these procedures by making observation and gathering data. The data is not the procedure, it is a proxy for the procedure that provides us something to work with to comprehend the procedure. 

The strategies we leverage to make observations and gather or sample data also introduce uncertainties into the data. Combined with the inherent arbitrariness in the real-world procedure, we now possess dual sources of arbitrariness in our data. 

Provided the data we have gathered, we cleanse it, develop a model and attempt to say something about the procedures in the real world. 

For instance, we might make a forecast or detail the relationships amongst elements within the procedure. 

This is referred to as statistical inference. We go from a real world stochastic process, gather and model the process in data, and come back to the procedure in the world and say something about it. 

Statistical Population 

Data belongs to a population (N). A data population is all potential observations that might be made. The population is abstract, an ideal. 

When you make observations or operate with data, you are operating with a sample of the population (n). If you are operating on a prediction problem, you are looking to ideally leverage n to characterize N so that you reduce the errors in the forecasts you make from other n your system will encounter. 

You must be meticulous in your selection and management of your sample. The size and qualities of the data will impact your ability to effectively characterize the problem, to make forecasts or detail the data. The randomness (biases) put forth during the collection of must be considered and even manipulated, managed, or rectified. 

Big Data 

The promise of big data is that you no longer require to be concerned about sampling data, that you can work with all the information. 

That you are operating with N and not n. This is incorrect and hazardous thinking. 

You are still operating with a sample. You can observe how this is the scenario. For instance, if you are modelling client data in a SaaS business, you are operating with a sample of the population that found and signed up for the service before modelling. Those caveats bias the information you are operating with. 

You must be meticulous to not over generalize your discoveries, to be cautious about claims beyond the information you have observed. For instance, the trends of all users of twitter do not represent the trends of all humans. 

In the other direction, big data enables you to model every individual entities, like one customer (n=1), leveraging all data gathered on that entity to date. This is a potent, exciting, and computationally demanding frontier. 

Statistical Models 

The planet is complex and we are required to simplify it with assumptions in order to comprehend it.  

A model is a simplification of a process in the real world. It will always be wrong, but it might be useful. 

A statistical model details the relationship amongst data attributes, like dependent variable with independent variables. 

You can perceive your data prior and put forth a model that details relationships amongst the data. 

You can also carry out machine learning algorithms that assume a variant of model of a particular form will detail the relationship and identify the parameters to fit the model to the data. This is where notions of a fit, overfitting and underfitting come from, where the model is too particular or not particular enough in its ability to generalize beyond observed data. 

Easier models are simpler to comprehend and leverage more than complicated models. As such, it is a good notion to begin with the simplest models for a problem and increase intricacy as you require. For instance, assume a linear form for your model prior to considering a non-linear, or a parametric prior to a non-parametric model. 


In this blog article, you obtain a brief crash course in critical ideas in statistics that you require when beginning in machine learning. 

Particularly, the ideas of statistical inference, statistical populations, how concepts from big data fit in, and statistical models. 

Take it slow, stats is a massive domain and you are not required to know everything. 

Don’t rush out and buy an undergraduate text on stats, at least, not at this point. It is a lot, and it is too soon. 

If you seeking additional info, we would recommend that you begin by reading the intro sections on stats in machine learning books, for instance, Chapter 2 of Doing Data Science: Straight Talk from the Frontline, from which this blog post draws inspiration. 

For additional data, consider taking a peek at some of the linked Wikipedia articles. 

Going one step further, Khan Academy has some amazing modules on statistics and probability. 

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