Sequential analysisIn statistics, sequential analysis or sequential hypothesis testing is statistical analysis where the sample size is not fixed in advance. Instead data are evaluated as they are collected, and further sampling is stopped in accordance with a pre-defined stopping rule as soon as significant results are observed. Thus a conclusion may sometimes be reached at a much earlier stage than would be possible with more classical hypothesis testing or estimation, at consequently lower financial and/or human cost.
Non-24-hour sleep–wake disorderNon-24-hour sleep–wake disorder (non-24 or N24SWD) is one of several chronic circadian rhythm sleep disorders (CRSDs). It is defined as a "chronic steady pattern comprising [...] daily delays in sleep onset and wake times in an individual living in a society". Symptoms result when the non-entrained (free-running) endogenous circadian rhythm drifts out of alignment with the light–dark cycle in nature. Although this sleep disorder is more common in blind people, affecting up to 70% of the totally blind, it can also affect sighted people.
Analysis of varianceAnalysis of variance (ANOVA) is a collection of statistical models and their associated estimation procedures (such as the "variation" among and between groups) used to analyze the differences among means. ANOVA was developed by the statistician Ronald Fisher. ANOVA is based on the law of total variance, where the observed variance in a particular variable is partitioned into components attributable to different sources of variation.
Cross-beatIn music, a cross-beat or cross-rhythm is a specific form of polyrhythm. The term cross rhythm was introduced in 1934 by the musicologist Arthur Morris Jones (1889–1980). It refers to a situation where the rhythmic conflict found in polyrhythms is the basis of an entire musical piece. The term "cross rhythm" was introduced in 1934 by the musicologist Arthur Morris Jones (1889–1980), who, with Klaus Wachsmann, took-up extended residence in Zambia and Uganda, respectively, as missionaries, educators, musicologists, and museologists.
Time signatureThe time signature (also known as meter, metre, and measure signature) is a convention in Western music notation to specify how many of a particular note value are contained in each measure (bar). The time signature is a notational device representing the meter, an auditory feature of the music. In a music score the time signature appears at the beginning as a time symbol or stacked numerals, such as or (read common time or four-four time, respectively), immediately following the key signature (or immediately following the clef symbol if the key signature is empty).
Duration (music)In music, duration is an amount of time or how long or short a note, phrase, section, or composition lasts. "Duration is the length of time a pitch, or tone, is sounded." A note may last less than a second, while a symphony may last more than an hour. One of the fundamental features of rhythm, or encompassing rhythm, duration is also central to meter and musical form. Release plays an important part in determining the timbre of a musical instrument and is affected by articulation.
Music and mathematicsMusic theory analyzes the pitch, timing, and structure of music. It uses mathematics to study elements of music such as tempo, chord progression, form, and meter. The attempt to structure and communicate new ways of composing and hearing music has led to musical applications of set theory, abstract algebra and number theory. While music theory has no axiomatic foundation in modern mathematics, the basis of musical sound can be described mathematically (using acoustics) and exhibits "a remarkable array of number properties".
