Statistics - Skew (-ed Distribution|Variable)

Thomas Bayes


The skew is where is few.

  • A positive skew means that you have few data at the right of the distribution.
  • A negative skew means that you have few data at the left of the distribution.

Skewed Distribution

When distributions are skewed, the most accurate measure of central tendency is the median

When variables are inherently positive or strongly skewed, such as the weight of a person or the price of a share, may be better described by other distributions, such as:

  • the log-normal distribution
  • or the Pareto distribution.


A measure of the extent to which a pmf or pdf “leans” to one side of its mean.

Discover More
Data System Architecture
Data Partition - Horizontal

Horizontal partitions cuts the data by row. Vertical partition Partition is what enable parallelism. Do not under partition - Partitioning on columns with only a few values can cause few partitions...
Utah Teapot
Data Visualisation - Histogram (Frequency distribution)

A histogram is a type of graph generally used to visualize a distribution An histogram is also known as a frequency distribution. Histograms can reveal information not captured by summary statistics...
Distribution - (Mean|Average) (M| | )

The average is a measure of center that statisticians call the mean. To calculate the mean, you add all numbers and divide the total by the number of numbers (N). The mean is not resistant. The...
Random Generator
Number - Random (Stochastic|Independent) or (Balanced)

Think of randomness as a lack of pattern. Something random should be unpredictable. We shouldn’t be able to predict the next value of the sequence The degree to which a system has no pattern is known...
Card Puncher Data Processing
Oracle Database - Selectivity

The first measure of the plan_estimator, selectivity, represents a fraction of rows from a row set. The row set can be a base table, a view, or the result of a join or a GROUP BY operator. The selectivity...
Card Puncher Data Processing
Oracle Database - Statistics - Columns

For columns with skewed data, you should collect histograms. Statistics Col Description NUM_DISTINCT Number of distinct values (NDV) LOW_VALUE Low value HIGH_VALUE High value NUM_NULLS Number...
Histogram Height Balanced Uniform Distribution
Oracle Database - Statistics - Histogram (Column statistics)

Data Dictionary Column statistics may be stored as histograms. These histograms provide accurate estimates of the distribution of column data. Histograms provide improved selectivity estimates in the presence...
Oracle Database Sql Processing
SQL Engine - Optimizer Statistics

In order to make the best execution plan, the optimizer uses statistics on the database objects and the computer system. data dictionary Optimizer statistics are always treated as estimates and can become...
Data System Architecture
Statistics - (Data|Data Set) (Summary|Description) - Descriptive Statistics

Summary are a single value summarizing a array of data. They are: selected or calculated through reduction operations. They are an important element of descriptive analysis One of the most important...
Thomas Bayes
Statistics - Central limit theorem (CLT)

The Central_limit_theoremcentral limit theorem (CLT) is a probability theorem (unofficial sovereign) It establishes that when: random variables (independent) (estimate of a random process) are added...

Share this page:
Follow us:
Task Runner