# Category: Data Science: Statistics

## Applied statistics

Applied statistics Applied statistics is used to solve practical problems with data. For each type of experiment in applied statistics, specific steps must be followed to collect, analyse and interpret the data.   Though applied statistics and data science can overlap at times, it is usually the case that applied statistics is being used by Read More …

## Nonparametric statistics

Nonparametric statistics When your data does not fit to a normal distribution, nonparametric statistical methods are required. A number of the nonparametric tests use ordinal data rather than numerical, with the data ranked and sorted in order. For example, nonparametric statistics could analyse a Likert scale ranking survey responses: Strongly Agree, Agree, Neither agree nor Read More …

## Z-tests

Z-tests A one-sample z-test assesses the sample mean of a variable against a population mean, whilst a two-sample z-test compares the mean from two different groups. The differences are compared with the estimated standard error to conclude whether there is evidence that the population means differ.   It is generally accepted that a sample size Read More …

## T-tests

T-tests T-tests can be used with any sample sizes and the mean or standard deviation of the population do not need to be known. Although the t-test relies on the assumption of a normal distribution, its probability values are based on the t-distribution. The test is appropriate when either the population is normal or the Read More …

## Confidence intervals

Confidence intervals A confidence interval describes a range of values that are likely to include the true value for a population. The upper and lower confidence limits are the two numbers that make up the range of the interval. Confidence intervals do not provide certain answers, they are an estimate based on a sample.   Read More …

## Analysis techniques

Time series analysis General term for trending findings over a time period, usually in a graphical format, which can be used to make predicted forecasts for the future.     Survival analysis A statistical method of estimating the expected duration of time until an event occurs. Example: A human beings expected lifespan being assessed using Read More …

## Algebra

Algebra Algebra deals with letters and symbols and rules to manipulate those symbols used to represent numbers and quantities within formulae and equations.   Algebraic expressions commonly include a mixture of letters, numbers and other symbols. E.g. x + 5 = y. To represent multiplication you don’t need to use a multiplication symbol, 5 multiplied Read More …

## Trigonometry

Trigonometry Trigonometry is the study of triangles. Three trigonometric functions that are specific to right-angled triangles are sine, cosine and tangent, often shortened to sin, cos and tan.   Firstly it is important to understand the terms used to describe the three sides of a right triangle:Hypotenuse – The side opposite the right angle, always Read More …

## Shapes and area

Shapes and area Triangles can be defined by the length of their sides or by their angle types.   Scalene triangles are where none of the sides are equal. Isosceles triangles are where at least two of the sides have equal length. Equilateral triangles have all three sides of equal length.   All triangles have Read More …

## Lines and angles

Lines Parallel lines go in the same direction but do not intersect. E.g. two sides of a piece of paper.   Perpendicular lines are lines that intersect at a right angle. E.g. two lines crossing to form an ‘x’, if any one of the angles are 90° then all four of the angles will be Read More …