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A single-access key (also called a sequential key or an analytical key), has a fixed structure and sequence. The user must begin at the first step of the key and proceed until the end. A single-access key has steps that consist of two mutually exclusive statements (leads) is called a dichotomous key. Most single-access keys are dichotomous. [3]
In phylogenetics, a single-access key (also called dichotomous key, sequential key, analytical key, [1] or pathway key) is an identification key where the sequence and structure of identification steps is fixed by the author of the key. At each point in the decision process, multiple alternatives are offered, each leading to a result or a ...
In a diagnostic key, the branching structure of the key should not be mistaken for a phylogenetic or cladistic branching pattern. All single-access keys form a decision tree (or graph if reticulation exists), and thus all such keys have a branching structure. "Branching key" may therefore occasionally be used as a synonym for single-access key.
Four types of response scales for closed-ended questions are distinguished: Dichotomous, where the respondent has two options. The dichotomous question is generally a "yes/no" close-ended question. This question is usually used in case of the need for necessary validation. It is the most natural form of a questionnaire.
The terms "tabular key" and "matrix key" are best limited to a tabular presentation format of multi-access keys. [3] The term "synoptic key" has an older definition, defining it as a key reflecting taxonomic classification and opposed to diagnostic keys arranged solely for the convenience of identification. [1]
This is not easy to calculate, and the biserial coefficient is not widely used in practice. A specific case of biserial correlation occurs where X is the sum of a number of dichotomous variables of which Y is one. An example of this is where X is a person's total score on a test composed of n dichotomously scored items. A statistic of interest ...
Polychotomous key refers to the number of alternatives which a decision point may have in a non-temporal hierarchy of independent variables. The number of alternatives are equivalent to the root or nth root of a mathematical or logical variable.
A closed-ended question is any question for which a researcher provides research participants with options from which to choose a response. [1] Closed-ended questions are sometimes phrased as a statement that requires a response. A closed-ended question contrasts with an open-ended question, which cannot easily be answered with specific ...