# IAS: Statistics Glossary L to P

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## Statistics Glossary: L to P

- Large sample: A sample whose size is above 30.
- Least squares: Any line or curve fitting model, that minimizes the squared distance of the data points to the line.
- Leptokurtic: If the curve is more peaked than the normal curve it is called Leptokurtic.
- Lower Quartile (Q1) : It is the size of the 25
^{th}observation when the data is arranged in ascending or descending order or the 25^{th}percentile of a set of measures. - Lines of Regression: In the scatter plot, if the variables are highly correlated then the dots lie in a narrow strip. If the strip is nearly a straight line then it is called a line of regression.
- Level of Significance: The probability level below which we reject the hypothesis.
- Mean: It is the some of the measures in a distribution by their number.
- Mathematical Expectations: The sum of the products of values of a variable and their respective probabilities
- Measures of Central Tendency: The descriptive measures which indicate the centered values of a set of observations.
- Measure of variation: It is the descriptive measures which points out the spread of values in a set of values.
- Median (Q2) : The value or the size of the central item of the arranged data or the middle i.e.. . 50
^{th}percentile of the ordered distribution. - Mode: It is the size of the item which occurs most frequently in a distribution.
- Mutually Exclusive: Outcomes such that the occurrence of one preclude the occurrence of the other.
- Moments: The arithmetic mean of the various powers of the deviations in any distribution.
- Negative Relationship: In a relationship between two variables when one increases the other decreases or vice-versa.
- Nominal: A scale using numbers, symbols, or titles to designate the different sub-class.
- Normal Distribution: It is the limiting form of the binomial distribution when the number of trials is very large and the probability of success and failure is very small.
- Non-parametric Test: Statistical test used, when the population cannot be assume to be normal or when the level of measurements is ordinal or less.
- Null-Hypothesis: The opposite or reverse of the researcher՚s hypothesis.
- Ogive: A graphic representation, that displays a running total.
- One-Tail Test (One sided Test) : A test that predicts that one value is higher than the other.
- Ordinal: It is a scale which uses numbers or symbols to rank the intervals are unspecified.
- Out-lier: The points of the data, that fall far away from most of the other points of the data.
- Parameter: A characteristic of population.
- Percentile: It is a value in an order set of measurement, that is calculated on the basis of percentage.
- Pie-chart: It is a circular diagram which is a circle (pie) divided by radii (like slices of a cake or pie)
- Platy kurtic: If the curve is flat-topped when compared to the normal curve then it is a platy kurtic curve.
- Point Estimate: A number computed from a sample, representing a population parameter.
- Population: A group of phenomena having something in common.
- Positive Correlation: A relationship between two variables such that when one increases the other also increases or when one decreases the other also decreases.
- Power: When a hypothesis is fall, the probability that a test will reject the null hypothesis is called Power.
- Probability: A quantity measure of the chances of an outcome or outcomes of a random experiment.
- Probability-Distribution: An unbroken (smooth) curve which indicates the frequency distribution of a continuous random variable.