Key Concepts and Definitions in Statistics
Classified in Mathematics
Written at on 
English with a size of 2.95 KB.
Key Concepts and Definitions in Statistics
Statistics - The science of collecting, organizing, analyzing, and interpreting data for the purpose of making more effective decisions.
Levels of Measurement - Nominal, ordinal, interval, and ratio levels of measurement.
Discrete Variables - Variables that can assume only certain values, and there are “gaps” between the values.
Inferential or Inductive Statistics - This facet of statistics deals with estimating a population parameter based on a sample statistic.
Statistic - A characteristic of a sample.
Parameter - A characteristic of a population.
Frequency Distribution - A grouping of data into classes showing the number of observations in each of the mutually exclusive and collectively exhaustive classes.
Pie Chart - A circular chart that shows the proportion or percentage that each class represents of the total number of frequencies.
Frequency Table - A grouping of qualitative data into mutually exclusive classes showing the number of observations in each class.
Mutually Exclusive; Exhaustive - A property of a set of categories such that an individual, object, or measurement is included in only one category. The categories cover every possible state.
Cumulative Frequency Distributions - Each class is summed with the class prior in a frequency distribution.
Empirical Rule - For a symmetrical, bell-shaped frequency distribution, approximately 68% of the observations lie within ±1 standard deviation of the mean; about 95% of the observations lie within ±2 standard deviations of the mean; and practically all (99.7%) lie within ±3 standard deviations of the mean.
Mean - The average. Sum all observations and divide by the number of observations.
Dispersion - Refers to the spread of the data around the mean.
Standard Deviation - A measure of dispersion. It is the square root of the variance.
Variance - The mean of the squared deviation from the mean of all observations. It is a measure of dispersion.
Box Plot - A graphic display that shows the general shape of a variable's distribution. It is based on five descriptive statistics: the maximum and minimum values, the first and third quartiles, and the median.
3rd Quartile - The 75th percentile used in a box plot.
Skewness - A measure of the asymmetry of a distribution of data.
Contingency Table - A table used to classify observations according to two characteristics. For example, characteristics such as gender and highest degree earned for a sample of stockbrokers are cross-classified into a table.