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    The UCLA VRP has compiled a list of terms often used when discussing redistricting, defining them in the dictionary below. The dictionary is organized in alphabetical order.

    • Advisory Committee: A structured way for individual residents to share opinions and perspectives, study issues, and develop recommendations in a focused, small group structure. An advisory committee balances the formal board to more effectively reflect the views of residents.
    • Apportionment: The process of assigning the number of legislative seats that will represent pre-existing political subdivisions. Some jurisdictions assign districts based on geographical boundaries and therefore continue to use the term apportionment for their redistricting process.
    • At-large: When a district elects more than one member, all candidates run against each other on one ballot and are elected by the whole population of the district. Sometimes this happens with entire governing bodies for municipalities. In this scenario, all residents of the municipality are eligible to vote for every single elected official on the governing body. Compare this to district-based elections, where officials are elected from single-member districts.
    • BISG: Bayesian Improved Surname Geocoding or BISG is a statistical method that is used to analyze whether racially polarized voting (see below) exists in a jurisdiction. BISG relies on utilizing a combination of census surname analysis and census block-level racial demographics to provide an overall probability assessment of a voter’s race or ethnicity.
    • Coalition District: A district where more than one protected minority group combined forms a majority in a district.
    • Compactness: Having the minimum distance between all the parts of a constituency. A circle, square, or hexagon are examples of a very compact district. Measuring compactness can avoid the process of gerrymandering (see gerrymandering).
    • Communities of Interest: Geographical areas, such as neighborhoods or regions, where the residents have shared demographic and/or political interests that do not necessarily match the boundaries of a political subdivision.
    • Contiguousness or Contiguity: A single, unbroken shape in which all parts of the district are attached and connected to each other. Two areas touching at corners are typically not considered contiguous.
    • Cracking: Spreading like-minded voters apart across multiple districts to dilute their voting power in each. This denies the group representation in multiple districts.
    • District: The boundaries that define the constituency from which a public official is elected.
    • Ecological Inference or “EI”: Ecological Inference or EI is a statistical method that is used to determine if racially polarized voting (see below) is occurring in a jurisdiction. It has been considered the benchmark in evaluating racial polarization in voting. EI use aggregated ecological data such as precinct vote totals and racial demographics and use statistical methods to find voting patterns by regressing candidate choices against racial demographics in a jurisdiction.
    • Gerrymandering: A plan or a district intentionally drawn to manipulate district lines to advantage one group or party over another, generally identified by inexplicable district shapes. Common types of gerrymandering include:
      • Racial gerrymandering, which disadvantages a certain racial group; and
      • Partisan gerrymandering, which disadvantages voters from a particular political party.
    • Independent Commission: A statutory or constitutional body charged with researching, advising, or enacting policy made up entirely of individuals who are not elected officials or their family members or staff. These entities are generally made up of equal numbers of individuals from the major political parties who are voters in the state or locality that is being redistricted.
    • Majority-Minority District: Districts in which a racial or language minority constitute a majority of the electorate. They are designed to ensure that the minority community has a legitimate chance to elect the candidate of their choice.
    • Multi-Member District: A single district that elects two or more members to a legislative body.
    • Malapportionment: Districts that are poorly apportioned, especially divided, organized, or structured in a manner that prevents large sections of a population from having equitable representation in a legislative body. This term normally arises in the context of one person, one vote violations where the districts for a governing body do not have equal populations.
    • Maximum Deviation: The measure of how much a district or plan varies from the ideal population, defined as the total population divided by the total number of representatives (and multiplied by the number of representatives elected by that district, in the case of multi-member districts), per district. The deviation can be expressed as an absolute number or as a percentage.
    • Packing: A term used when one group is consolidated as a super-majority in a smaller number of districts, thus reducing its electoral influence.
    • Single Member District: District electing only one representative to the legislative body rather than two or more. (see multi-member district)
    • Racially Polarized Voting (RPV): Racially polarized voting exists when voters of different racial or ethnic groups exhibit very different candidate preferences in an election. In other words, voters of different groups are voting in opposite directions rather than in a coalition. RPV measures the outcomes of voting patterns and determines whether patterns exist based on race/ethnicity.
    • Reapportionment (vs. Redistricting): Reapportionment is the process of reassigning representation based on population. Redistricting is to set up new district lines after reapportionment is complete.
    • Unity Map: A map typically recommended by a coalition of various minority advocacy groups, designed to give minority groups the most influential voice in the electoral process. A unity map should take into consideration the growth of minority communities to keep these areas united.
    • Vote Dilution: The process of drawing election districts in ways that improperly dilute minorities’ voting power. Two typical forms of vote dilution involve “cracking” and/or “packing.” This also describes the failure of a redistricting body to draw a majority-minority or coalition district when it is required by Section 2 of the Voting Rights Act.