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Data and Statistics

Data Parameters

Before looking for data, it often helps to define specific parameters you're looking for. These include:

  • Subjects: Exactly what do you want counted?
  • Time Coverage: What time period(s) should the statistics cover?
  • Geographic Coverage: What geographic area(s) should the statistics cover?
  • Cross-tabulation: Do you want the data broken down by characteristics like sex, age, income, occupation, or industry?

It often helps to draw up an example of the table you're looking for. What elements appear on the X axis? the Y axis? What units of measurement do you want? Do you need some parameters to be grouped in specific increments? You may not be able to find numbers that exactly match your example, but knowing which elements you want will help your search tremendously.

Time Coverage

Do you need the numbers broken down by decade, year, or month? Are you looking for the most recent data or historical data? Things to watch out for:

  • Most government statistics provide snapshots, not historical time series, so you may have to look in multiple volumes to get data over time.
  • There's usually a lag between data collection and publication. For example, the Census is done on every tenth year, but the most detailed reports take 3–5 years to be compiled and published. In many cases up-to-the-minute statistics are not available.
  • Definitions can change over time, even in the same statistical source. Be sure to check the exact definitions of what's being counted in each source you consult.

Geographic Coverage

Typical geographic areas include nations, states/provinces, regions, metropolitan areas, counties, and cities. Things to watch out for:

  • Boundaries can change over time, so be sure to check associated definitions or maps to ensure consistency.
  • Statistics for small areas (neighborhoods, zip codes, or census tracts) present unique challenges.