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 Statistical Learning


Implementing the Gradient Descent Algorithm in R

@machinelearnbot

The intercept is the point on the y-axis where the value of the predictor x is zero. In order to apply the linear hypothesis to a dataset with the end aim of modelling the situation under investigation, there needs to be a linear relationship between the variables in question. A simple scatterplot is an excellent visual tool to assess linearity between two variables. Below is an example of a linear relationship between miles per gallon (mpg) and engine displacement volume (disp) of automobiles which could be modelled using linear regression. Note that there are various methods of transforming non-linear data to make them appear more linear such as log and square root transformations but we won't discuss those here.


The 10 Algorithms Machine Learning Engineers Need to Know

#artificialintelligence

It is no doubt that the sub-field of machine learning / artificial intelligence has increasingly gained more popularity in the past couple of years. As Big Data is the hottest trend in the tech industry at the moment, machine learning is incredibly powerful to make predictions or calculated suggestions based on large amounts of data. Some of the most common examples of machine learning are Netflix's algorithms to make movie suggestions based on movies you have watched in the past or Amazon's algorithms that recommend books based on books you have bought before. So if you want to learn more about machine learning, how do you start? For me, my first introduction is when I took an Artificial Intelligence class when I was studying abroad in Copenhagen. My lecturer is a full-time Applied Math and CS professor at the Technical University of Denmark, in which his research areas are logic and artificial, focusing primarily on the use of logic to model human-like planning, reasoning and problem solving.


The 10 Statistical Techniques Data Scientists Need to Master

@machinelearnbot

Regardless of where you stand on the matter of Data Science sexiness, it's simply impossible to ignore the continuing importance of data, and our ability to analyze, organize, and contextualize it. Drawing on their vast stores of employment data and employee feedback, Glassdoor ranked Data Scientist #1 in their 25 Best Jobs in America list. So the role is here to stay, but unquestionably, the specifics of what a Data Scientist does will evolve. With technologies like Machine Learning becoming ever-more common place, and emerging fields like Deep Learning gaining significant traction amongst researchers and engineers -- and the companies that hire them -- Data Scientists continue to ride the crest of an incredible wave of innovation and technological progress. While having a strong coding ability is important, data science isn't all about software engineering (in fact, have a good familiarity with Python and you're good to go). Data scientists live at the intersection of coding, statistics, and critical thinking.


[D] What's the difference between data science, machine learning, and artificial intelligence? โ€ข r/MachineLearning

#artificialintelligence

Practically they are the same thing. DS: stats like avg, median and sum are also metrics considered to be tools in Data Science. Data science is a "concept to unify statistics, data analysis and their related methods" in order to "understand and analyze actual phenomena" with data.[3] It employs techniques and theories drawn from many fields within the broad areas of mathematics, statistics, information science, and computer science, in particular from the subdomains of machine learning, classification, cluster analysis, data mining, databases, and visualization. Making a visualization tool can also be a data science solution.


Controlling for Unobserved Confounds in Classification Using Correlational Constraints

arXiv.org Artificial Intelligence

As statistical classifiers become integrated into real-world applications, it is important to consider not only their accuracy but also their robustness to changes in the data distribution. In this paper, we consider the case where there is an unobserved confounding variable $z$ that influences both the features $\mathbf{x}$ and the class variable $y$. When the influence of $z$ changes from training to testing data, we find that the classifier accuracy can degrade rapidly. In our approach, we assume that we can predict the value of $z$ at training time with some error. The prediction for $z$ is then fed to Pearl's back-door adjustment to build our model. Because of the attenuation bias caused by measurement error in $z$, standard approaches to controlling for $z$ are ineffective. In response, we propose a method to properly control for the influence of $z$ by first estimating its relationship with the class variable $y$, then updating predictions for $z$ to match that estimated relationship. By adjusting the influence of $z$, we show that we can build a model that exceeds competing baselines on accuracy as well as on robustness over a range of confounding relationships.


Noisy Expectation-Maximization: Applications and Generalizations

arXiv.org Machine Learning

We present a noise-injected version of the Expectation-Maximization (EM) algorithm: the Noisy Expectation Maximization (NEM) algorithm. The NEM algorithm uses noise to speed up the convergence of the EM algorithm. The NEM theorem shows that injected noise speeds up the average convergence of the EM algorithm to a local maximum of the likelihood surface if a positivity condition holds. The generalized form of the noisy expectation-maximization (NEM) algorithm allow for arbitrary modes of noise injection including adding and multiplying noise to the data. We demonstrate these noise benefits on EM algorithms for the Gaussian mixture model (GMM) with both additive and multiplicative NEM noise injection. A separate theorem (not presented here) shows that the noise benefit for independent identically distributed additive noise decreases with sample size in mixture models. This theorem implies that the noise benefit is most pronounced if the data is sparse. Injecting blind noise only slowed convergence.


Autoencoders and Probabilistic Inference with Missing Data: An Exact Solution for The Factor Analysis Case

arXiv.org Machine Learning

Latent variable models, like factor analysis and "deeper" versions such as the variational autoencoder (VAE, Kingma and Welling 2014; Rezende et al. 2014) and generative adversarial networks (GANs, Goodfellow et al. 2014), are a compelling approach to modelling structure in complex high-dimensional data such as images. One important use case of such models is when some part of the observable data is missing--such as when some part of an image is not observed. In this case we would like to use the latent variable model to "inpaint" the missing data. Another example is modelling 3-D volumetric data--we may have observations of an object from one viewpoint, and wish to make inferences about the whole 3-D object. The VAE is composed of two parts, an encoder (or recognition) network that predicts the distribution of the latent variables given the data, and a decoder (or generative) model that maps from the latent variables to the visible variables.


Logistic Regression, Decision Tree and Neural Network in R

@machinelearnbot

In this course, we cover two analytics techniques: Descriptive statistics and Predictive analytics. For the predictive analytic, our main focus is the implementation of a logistic regression model a Decision tree and neural network. We well also see how to interpret our result, compute the prediction accuracy rate, then construct a confusion matrix . By the end of this course, you will be able to effectively summarize your data, visualize your data, detect and eliminate missing values, predict futures outcomes using analytical techniques described above, construct a confusion matrix, import and export a data.


Regularization in Machine Learning

@machinelearnbot

One of the major aspects of training your machine learning model is avoiding overfitting. The model will have a low accuracy if it is overfitting. This happens because your model is trying too hard to capture the noise in your training dataset. By noise we mean the data points that don't really represent the true properties of your data, but random chance. Learning such data points, makes your model more flexible, at the risk of overfitting.


Statistics with R - Advanced Level Udemy

#artificialintelligence

If you want to learn how to perform real advanced statistical analyses in the R program, you have come to the right place. Now you don't have to scour the web endlessly in order to find how to do an analysis of covariance or a mixed analysis of variance, how to execute a binomial logistic regression, how to perform a multidimensional scaling or a factor analysis. Everything is here, in this course, explained visually, step by step. So, what's covered in this course? First of all, we are going to study some more techniques to evaluate the mean differences.