Free reference · 596 entries
The words, before the course.
Short, plain definitions of the terms that turn up in statistics and data science — what they mean, and how they relate to each other. Nothing to sign in for.
20 of 596 entries under N
- Naive bayes classifierA full Bayesian classifier is a supervised learning technique that assigns a class to a record by finding other records with attributes just like it has, and finding the most prevalent class among them.
- Natural LanguageA natural language is what most people outside the field of computer science think of as just a language (Spanish, English, etc.).
- Nearest Neighbor ClusteringThe nearest neighbor clustering is a synonym for single linkage clustering.
- Negative BinomialThe negative binomial distribution is the probability distribution of the number of Bernoulli (yes/no) trials required to obtain r successes.
- Netflix PrizeThe Netflix prize was a famous early application of crowdsourcing to predictive modeling. In 2006, Netflix published customer movie rating data and challenged analysts to come up with a predictive model…
- Neural NetworkA neural network (NN) is a network of many simple processors (“units”), each possibly having a small amount of local memory.
- NodeA node is an entity in a network. In a social network, it would be a person. In a digital network, it would be a computer or device.
- NoiseThe noise is the component of the observed data (e.g. of a time series) that is random and carries no useful information.
- Nominal ScaleA nominal scale is really a list of categories to which objects can be classified. For example, people who receive a mail order offer might be classified as “no response,” “purchase and pay,” “purchase but…
- Non-parametric RegressionNon-parametric regression methods are aimed at describing a relationship between the dependent and independent variables without specifying the form of the relationship between them a priori.
- Nonlinear FilterA nonlinear filter is the filter whose output is a nonlinear function of the input. By definition, any filter that is not a linear filter is a nonlinear filter.
- Nonparametric ANOVA StatisticSee Mean Score Statistic.
- Nonparametric TestsIn statistical inference procedures (hypothesis tests and confidence intervals), nonparametric procedures are those that are relatively free of assumptions about population parameters.
- Nonrecursive FilterIn nonrecursive filters, the output at the moment is a function of only input values corresponding to the time moments : A complementary concept is recursive filter.
- Nonstationary time seriesA time series x_t is called to be nonstationary if its statistical properties depend on time.
- Normal DistributionThe normal distribution is a probability density which is bell-shaped, symmetrical, and single peaked.
- NormalityNormality is a property of a random variable that is distributed according to the normal distribution.
- Normality TestsNormality tests are tests of whether a set of data is distributed in a way that is consistent with a normal distribution.
- NoSQLA NoSQL database is distinguished mainly by what it is not – it is not a structured relational database format that links multiple separate tables.
- Null HypothesisIn hypothesis testing, the null hypothesis is the one you are hoping can be disproven by the observed data.
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