**Poisson Distribution** – A special instance of a binomial distribution, in which the probability for a specific event is extremely small (for example: an accident). See also: Binomial distribution

**Probability Distribution** – A distribution that expresses the probability of value X as a function of X. See also: Binomial distribution

**Sample distribution** – Syn: Sampling distribution A special sort of probability distribution. The distribution of population according to values of specific sample statistics (for example: proportion, average, variance), that can be generated from a random sample taken from a specified population. See also: Proportion/Variance

**Skewed Distribution** – Data are not always symmetrically distributed. For example: most traffic accidents occur in the youngest age group. See also: J-shaped distribution

**Sub-normal** – A group of people or observations in a research project that fall below a certain norm. See also: Above average

**U-shaped Distribution** – A frequency distribution that in a graph assumes the shape, more or less, of the letter “U.” it does not necessarily have to be entirely symmetrical. The maximum frequency are positioned at both extremities of the variable. See also: Frequency distribution/Jshaped distribution

**Unimodal** – A frequency distribution with one single mode. In a graph, it is expressed as a single “peak.” For example, the majority of people going to movies are in the age class 18-25 years. See also: Bimodal/Frequency Distribution/Mode

**Univariate Distribution** – The distribution of a single variable, as distinct from bivariate, trivariate or multivariate distributions. See also: Variable/Multivariate distribution

**Bar Chart** – Syn: Bar diagram/Bar graph/Black diagram/Histogram See: Block diagram

**Bar Diagram** – Syn: Block Diagram/Bar chart/Bar graph/Histogram Visual representation of quantities consisting of a series of continuous rectangles proportional to the data it represents. See also: Diagram

**Bar Graph** – Syn: Bar Diagram/Block Diagram/Bar chart/Histogram See: Block Diagram

**Base Line** – The horizontal line in a graph. It corresponds with a simple basic measurement of the variable on the horizontal axis. The base line value is usually O or is transformed to O.

**Block Diagram** – Syn: Histogram/Bar Graph/Bar Graph A graph that is constructed from vertically placed rectangles, positioned next to one another on a common line. When the pictured characteristics are quantitative variables. When the block diagram is used to display frequency distribution, it is sometimes termed a histogram.

**Circular Chart** – Syn: Pie Chart A method for the representation of information in which the parts of a whole are pictured as sectors of a circle. The angles of the sectors are proportional to the parts of the whole. Additional visual aid may be obtained from the use of colors or shading.

**Curvilinear Relation** – The relation between two variables shown as a curved line on a graph. The opposite of linear relation. See also: Linear relation

**Curvilinear Trend** – A trend that is not linear. Such a trend may assume any other shape. See also:Trend

**Data Matrix** – Any array of values depicted as a series of rows and columns representing variables and values they may take. See also: Correlation Matrix

**Decision Tree** – A (tree- shaped) graph that is used to picture decision possibilities and the consequences of special decisions, in terms of the probability that a specific event will occur.

**Diagram** – A pictorial graph having as its aim to visually clarify or show a numerical whole ( for example: table). See also: Flow diagram

**Flow Chart** – Syn: Route diagram/Flow diagram See: Flow diagram

**Flow Diagram** – Syn: Route diagram/Flow chart A schematic explanatory outline that shows (using arrows) the progress of a process, step b step – for example, the manner in which a product gets to the final consumer.

**Frequency Polygon** – A diagram that shows the shape of a frequency distribution. The frequencies are represented as horizontal axes against the value of the variables as vertical axis.

**Graph** – Graphic representation of a statistical distribution. Its purpose is to render a distribution (more) visually accessible. See also: Frequency distribution

**Histogram** – Syn: Block diagram/Bar graph/Bar chart See: Block Diagram

**Least Squares Method** – Statistical method for obtaining an objectively appropriate form of a linear trend for a series of data.

**Linear Relation** – A relation between two variables that can be shown as a straight line on a graph. The opposite of a curvilinear relation. See also: Curvilinear Relation

**Pictograph** – That kind of graph in which the subject or concept is represented by means of a small picture. Such graphs can stimulate the imagination. Often, however, they are less than ideally precise or readable. For example: a population graph in which 1 million people are pictorially represented by a single small human form (and half a million by half a single small human form).