Index

An index is an indirect shortcut derived from and pointing into a greater volume of values, data, information or knowledge. Index may refer to:

Business

Publishing

Database index

A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure. Indexes are used to quickly locate data without having to search every row in a database table every time a database table is accessed. Indexes can be created using one or more columns of a database table, providing the basis for both rapid random lookups and efficient access of ordered records.

An index is a copy of select columns of data from a table that can be searched very efficiently that also includes a low-level disk block address or direct link to the complete row of data it was copied from. Some databases extend the power of indexing by letting developers create indices on functions or expressions. For example, an index could be created on upper(last_name), which would only store the upper case versions of the last_name field in the index. Another option sometimes supported is the use of partial indices, where index entries are created only for those records that satisfy some conditional expression. A further aspect of flexibility is to permit indexing on user-defined functions, as well as expressions formed from an assortment of built-in functions.

Index (statistics)

In statistics and research design, an index is a composite statistic – a measure of changes in a representative group of individual data points, or in other words, a compound measure that aggregates multiple indicators. Indexes summarize and rank specific observations.

Much data in the field of social sciences is represented in various indices such as Gender Gap Index, Human Development Index or the Dow Jones Industrial Average.

Item in indexes are usually weighted equally, unless there are some reasons against it (for example, if two items reflect essentially the same aspect of a variable, they could have a weight of 0.5 each).

Constructing the items involves four steps. First, items should be selected based on their face validity, unidimensionality, the degree of specificity in which a dimension is to be measured, and their amount of variance. Items should be empirically related to one another, which leads to the second step of examining their multivariate relationships. Third, indexes scores are designed, which involves determining their score ranges and weights for the items. Finally, indexes should be validateds, which involves testing whether they can predict indicators related to the measured variable not used in their construction.

Day (automobile)

The Day Utility was an automobile manufactured in Detroit, Michigan by the Day Automobile Company from 1911-14. The Day used a four-cylinder, 30 horsepower (22 kW) engine and shaft drive. Removal of the rear seat and doors allowed the car to be converted from a five-seater touring car to a light truck in one minute. As a truck, the Day was able to carry up to 1,000 lb (450 kg) in a 36-inch (910 mm) by 96-inch (2,400 mm) cargo space. The rear seat could be lifted away by triggering two spring locks. The Day had an advertised price of $950US.

References

Day language

Day is an Adamawa language of southern Chad, spoken by 50,000 or so people. Ethnologue reports that its dialects are mutually intelligible, but Blench (2004) lists Ndanga, Njira, Yani, Takawa as apparently separate languages.

References

Day (Michelangelo)

Day is a marble sculpture by Michelangelo, datable to 1526–31. It is a pair with Night on the tomb of Giuliano de' Medici in the Medici Chapel in San Lorenzo in Florence.

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