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The number 0 is represented by zero while null is a representation of an empty set {}. Hence in computer science a zero represents the outcome of a mathematical computation such as 2−2, while null is used for an undefined state (for example, a memory location that has not been explicitly initialised).
The null hypothesis is a default hypothesis that a quantity to be measured is zero (null). Typically, the quantity to be measured is the difference between two situations. For instance, trying to determine if there is a positive proof that an effect has occurred or that samples derive from different batches. [7] [8]
ℵ 0 (aleph-nought, aleph-zero, or aleph-null) is the cardinality of the set of all natural numbers, and is an infinite cardinal. The set of all finite ordinals, called ω or ω 0 (where ω is the lowercase Greek letter omega), has cardinality ℵ 0.
In science, a null result is a result without the expected content: that is, the proposed result is absent. [1] It is an experimental outcome which does not show an otherwise expected effect. This does not imply a result of zero or nothing, simply a result that does not support the hypothesis .
The null hypothesis tries to show that among two sets of data, there is no statistical difference between the results of doing one thing as opposed to doing a different thing. For an example of this, a scientist might be trying to prove that people who walk two miles a day have healthier hearts than people who walk less than two miles a day.
The null hypothesis is typically that some parameter (such as a correlation or a difference between means) in the populations of interest is zero. Our hypothesis might specify the probability distribution of X {\displaystyle X} precisely, or it might only specify that it belongs to some class of distributions.
In the past, "0" (the numeral zero) was occasionally used as a symbol for the empty set, but this is now considered to be an improper use of notation. [3] The symbol ∅ is available at Unicode point U+2205 ∅ EMPTY SET. [4] It can be coded in HTML as ∅ and as ∅ or as ∅. It can be coded in LaTeX as \varnothing.
For example, in linear algebra, the null space of a linear mapping, also known as kernel, is the set of vectors which map to the null vector under that mapping. In statistics, a null hypothesis is a proposition that no effect or relationship exists between populations and phenomena. It is the hypothesis which is presumed true—unless ...