Some examples of data imperfections include missing values, inconsistent string formatting e. When it comes to communicating, this means describing your findings, or the way techniques work to audiences, both technical and non-technical. Visualization-wise, it can be immensely helpful to be familiar with data visualization tools like matplotlib, ggplot, or d3.
Tableau has become a popular data visualization and dashboarding tool as well. It is important to not just be familiar with the tools necessary to visualize data, but also the principles behind visually encoding data and communicating information. How should you, as the data scientist, interact with the engineers and product managers?
What methods should you use? When do approximations make sense? For additional tips on how to succeed in the field, consider reading this post: 4 Types of Data Science Jobs. An interval can be asymmetrical because it works as lower or upper bound for a parameter left-sided interval or right sided interval , but it can also be asymmetrical because the two sided interval is built violating symmetry around the estimate. Sometimes the bounds for a confidence interval are reached asymptotically and these are used to approximate the true bounds.
Interpretation often comes down to the level of statistical significance applied to the numbers and often refers to the probability of a value accurately rejecting the null hypothesis sometimes referred to as the p-value. The standard approach  is to test a null hypothesis against an alternative hypothesis. A critical region is the set of values of the estimator that leads to refuting the null hypothesis. The probability of type I error is therefore the probability that the estimator belongs to the critical region given that null hypothesis is true statistical significance and the probability of type II error is the probability that the estimator doesn't belong to the critical region given that the alternative hypothesis is true.
The statistical power of a test is the probability that it correctly rejects the null hypothesis when the null hypothesis is false.
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Referring to statistical significance does not necessarily mean that the overall result is significant in real world terms. For example, in a large study of a drug it may be shown that the drug has a statistically significant but very small beneficial effect, such that the drug is unlikely to help the patient noticeably. Although in principle the acceptable level of statistical significance may be subject to debate, the p-value is the smallest significance level that allows the test to reject the null hypothesis.
This test is logically equivalent to saying that the p-value is the probability, assuming the null hypothesis is true, of observing a result at least as extreme as the test statistic. Therefore, the smaller the p-value, the lower the probability of committing type I error.
Some problems are usually associated with this framework See criticism of hypothesis testing :. Some well-known statistical tests and procedures are:. Exploratory data analysis EDA is an approach to analyzing data sets to summarize their main characteristics, often with visual methods. A statistical model can be used or not, but primarily EDA is for seeing what the data can tell us beyond the formal modeling or hypothesis testing task.
Misuse of statistics can produce subtle, but serious errors in description and interpretation—subtle in the sense that even experienced professionals make such errors, and serious in the sense that they can lead to devastating decision errors.
For instance, social policy, medical practice, and the reliability of structures like bridges all rely on the proper use of statistics. Even when statistical techniques are correctly applied, the results can be difficult to interpret for those lacking expertise. The statistical significance of a trend in the data—which measures the extent to which a trend could be caused by random variation in the sample—may or may not agree with an intuitive sense of its significance.
The set of basic statistical skills and skepticism that people need to deal with information in their everyday lives properly is referred to as statistical literacy. There is a general perception that statistical knowledge is all-too-frequently intentionally misused by finding ways to interpret only the data that are favorable to the presenter.
Misuse of statistics can be both inadvertent and intentional, and the book How to Lie with Statistics  outlines a range of considerations. In an attempt to shed light on the use and misuse of statistics, reviews of statistical techniques used in particular fields are conducted e. Warne, Lazo, Ramos, and Ritter Ways to avoid misuse of statistics include using proper diagrams and avoiding bias.
Thus, people may often believe that something is true even if it is not well represented. To assist in the understanding of statistics Huff proposed a series of questions to be asked in each case: . The concept of correlation is particularly noteworthy for the potential confusion it can cause. Statistical analysis of a data set often reveals that two variables properties of the population under consideration tend to vary together, as if they were connected.
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For example, a study of annual income that also looks at age of death might find that poor people tend to have shorter lives than affluent people. The two variables are said to be correlated; however, they may or may not be the cause of one another. The correlation phenomena could be caused by a third, previously unconsidered phenomenon, called a lurking variable or confounding variable.
For this reason, there is no way to immediately infer the existence of a causal relationship between the two variables. See Correlation does not imply causation.
Applied statistics comprises descriptive statistics and the application of inferential statistics. Mathematical statistics includes not only the manipulation of probability distributions necessary for deriving results related to methods of estimation and inference, but also various aspects of computational statistics and the design of experiments. Machine Learning models are statistical and probabilistic models that capture patterns in the data through use of computational algorithms. Statistics is applicable to a wide variety of academic disciplines , including natural and social sciences , government, and business.
Statistical consultants can help organizations and companies that don't have in-house expertise relevant to their particular questions. The rapid and sustained increases in computing power starting from the second half of the 20th century have had a substantial impact on the practice of statistical science. Early statistical models were almost always from the class of linear models , but powerful computers, coupled with suitable numerical algorithms , caused an increased interest in nonlinear models such as neural networks as well as the creation of new types, such as generalized linear models and multilevel models.
Increased computing power has also led to the growing popularity of computationally intensive methods based on resampling , such as permutation tests and the bootstrap , while techniques such as Gibbs sampling have made use of Bayesian models more feasible.
Dealing with Statistics: what you need to know
The computer revolution has implications for the future of statistics with new emphasis on "experimental" and "empirical" statistics. A large number of both general and special purpose statistical software are now available.
Traditionally, statistics was concerned with drawing inferences using a semi-standardized methodology that was "required learning" in most sciences. What was once considered a dry subject, taken in many fields as a degree-requirement, is now viewed enthusiastically. Statistical techniques are used in a wide range of types of scientific and social research, including: biostatistics , computational biology , computational sociology , network biology , social science , sociology and social research.
Some fields of inquiry use applied statistics so extensively that they have specialized terminology. These disciplines include:. In addition, there are particular types of statistical analysis that have also developed their own specialised terminology and methodology:. Statistics form a key basis tool in business and manufacturing as well.
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It is used to understand measurement systems variability, control processes as in statistical process control or SPC , for summarizing data, and to make data-driven decisions. In these roles, it is a key tool, and perhaps the only reliable tool. From Wikipedia, the free encyclopedia. For other uses, see Statistics disambiguation. Study of the collection, analysis, interpretation, and presentation of data.
Main article: Outline of statistics. Main article: Mathematical statistics. Main articles: History of statistics and Founders of statistics. Main article: Statistical data. Main articles: Statistical data type and Levels of measurement. Main article: Descriptive statistics.
Main article: Statistical inference. Main article: Interval estimation. Main article: Statistical significance. Student's t -test Time series analysis Conjoint Analysis. Main article: Exploratory data analysis. Main article: Misuse of statistics. Main article: Computational statistics. Main article: List of fields of application of statistics. Actuarial science assesses risk in the insurance and finance industries Applied information economics Astrostatistics statistical evaluation of astronomical data Biostatistics Business statistics Chemometrics for analysis of data from chemistry Data mining applying statistics and pattern recognition to discover knowledge from data Data science Demography statistical study of populations Econometrics statistical analysis of economic data Energy statistics Engineering statistics Epidemiology statistical analysis of disease Geography and geographic information systems , specifically in spatial analysis Image processing Jurimetrics law Medical statistics Political science Psychological statistics Reliability engineering Social statistics Statistical mechanics.
Abundance estimation Data science Glossary of probability and statistics List of academic statistical associations List of important publications in statistics List of national and international statistical services List of statistical packages software List of statistics articles List of university statistical consulting centers Notation in probability and statistics.
Foundations of statistics List of statisticians Official statistics Multivariate analysis of variance. Stanford Encyclopedia of Philosophy. Retrieved The American Statistician. The code book : the science of secrecy from ancient Egypt to quantum cryptography 1st Anchor Books ed. New York: Anchor Books. Answers Consulting. Economics Discussion.
Gordon; S. Gordon eds. Statistics for the Twenty-First Century.go here
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Investigating Statistical Concepts, Applications, and Methods. Duxbury Press. Kannan, V. Handbook of stochastic analysis and applications. New York: M. Theory of statistics Corr.