The SDI Over Time for Five Archetype Trends [Colour figure can be viewed at wileyonlinelibrary.com]
The State Democracy Index (SDI) comes from Grumbach.
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The five archetype trends among the 50 states include gradually increasing SDI (e.g., Arizona), gradually decreasing SDI (e.g., Oklahoma), abruptly decreasing SDI (e.g., North Carolina), fluctuating SDI (e.g., Michigan), and little change in SDI (e.g., Iowa).