Definition In statistics, the statistical data whether qualitative or quantitative, are generated or obtain through some measurement or some observational process. Measurement is essentially the task of assigning numbers to observations according to certain rules. The way in which the numbers are assigned to observations determines the scale of measurement being used. There are four level of measurements in statistics. They are- Nominal Level Ordinal Level Interval Level Ratio Level Nominal Level of Measurement All qualitative measurements are nominal, regardless of whether the cate ..read more

  Definition Forecasting is the process of making prediction of the future based on past and present data. In many cases a reliable forecast can be worth a lot of money, such as consistently and correctly guessing the behavior of the stock market for enough in advance to act upon such a guess. Objectives of forecasting In narrow sense, the objectives of forecasting is to produce better forecast. But in the broader sense, the objective is to improve organizational performance, more revenue, more profit, increased customer satisfaction etc. Better forecast by themselves are no inherent val ..read more

  Definition Inference comes from a word ‘infer’ which means that to draw a conclusion about a phenomenon on the basis of some information at hand. To make inference about a phenomenon through some statistical procedure is called statistical inference. Inference may be divided into two categories. They are- Inductive Inference Deductive Inference Inductive Inference By inductive inference we mean to draw a conclusion about a small part of the phenomenon and generalized it for the whole phenomenon. The research worker performs an experiment and obtain some data on the basis of the data ..read more

Time series data A time series data is a set of observation on the value that a variable takes of different time, such data may be collected at regular time intervals such as daily stock price, monthly money supply figures, annual GDP etc. Time series data have a natural temporal ordering. This makes time series analysis distinct from other common data analysis problems in which there is no natural order of the observation. In simple word we can say, the data which are collected in according to time is called time series data. On the other hand, the data which are collected by observing many ..read more

Definition An experiment is a well defined act or an investigation conducted to discover the underlying facts about a phenomenon, which are utilized to test some hypotheses of interest to verify the results of previous investigations. More precisely, an experiment is the process of data collection from a non-existent population to get answer to the certain problems under investigation. There are two types of experiment. They are- Absolute experiment: An absolute experiment is one in which the absolute value of some characteristic is determined. Sample survey belongs to absolute experiment ..read more

Definition The relationship between two or more random variables are generally defined as the correlation. It is the major part of bivariate analysis. When variables are found to be related, we often want to know how close the relationship is. The study of the relationship is known as correlation analysis. The primary objective of correlation is to measure the strength or degree of linear association between two or more variables. For example, we may be interested in measuring the relationship between the- Height and weight of the people of certain area. Ages of husband and their wives. A ..read more

  Skewness Literally, skewness means the 'lack of symmetry'. We study skewness to have an idea about the shape of the curve which we can draw with the help of the given data. A distribution is said to be skewed if- Mean, median, mode fall at different points, i.e, Mean ≠ Median ≠ Mode. Quartiles are not equidistant from median. The curve drawn with the help of the given data is not symmetrical but stretched more to one side than the other. The lack of symmetry in a distribution is always determined with reference to a normal distribution, which is always symmetrical. Any departure ..read more

  Discrete Probability Distributions There are some discrete probability distributions which are very important part of statistics are following- Bernoulli Distribution Binomial Distribution Poisson Distribution Negative Binomial Distribution Geometric Distribution Hypergeometric Distribution Multinomial Distribution Power Series Distribution Discrete Uniform Distribution Logarithmic Series Distribution Continuous Probability Distributions Some impotant continuous probability distributions are following- Uniform Distribution Normal Distribution Gamma Distribution Triangular Dist ..read more

Population variance and standard deviation The average of the square of the deviations taken from mean is called variance. The population variance is generally denoted by σ2and its estimate (sample variance) by s2. For N population values X1,X2,...,XN having the population mean μ, the population variance is defined as,   Where,  μ is the mean of all the observations in the population and N is the total number of observations in the population. Because the operation of squaring, the variance is expressed in square units and not of the original units. So, we can define ..read more

  Gamma Distribution A continuous random variable X is said to have a generalised gamma distribution with parameter α and β if its probability density fumction is defined as, Where α and β are two parameter and  α,β>0 ..read more