Data in everyday life: Voting

Beth SavageAmerican citizens who are 18 years or older have the right to vote in US general elections. However, it is the voter’s choice whether or not to exercise that right. This is in contrast to countries where voting is compulsory. In Australia, for example, under federal electoral law, all eligible citizens are required to vote in federal elections or pay a $20 penalty. Australia’s voter turnout percentages top 80%.

So what are the voter turnout percentages in the US? Does the voter turnout process exhibit normal or special cause variation? Let’s look at a control chart of voter turnout rates since 1960 (which was the first year that all 50 states were eligible to vote in the presidential election) to find the answers. Does it give any insight to what our 2016 election holds?

6 thoughts on “Data in everyday life: Voting

  1. Mr. Spock would say, “fascinating!”. Without the Range chart its hard to know if statistical control exists. The 2nd and 3rd data point in the outer zone above probably disqualifies the chart for statistical control. I will predict however, that 2016 will exceed 1960 (which I remember !)

    • Thanks for the comments Joe. I agree with you that an Individuals and Moving Range chart in most situations is preferable to an Individuals chart alone.

  2. Using the trend rule of 6 data points constantly increasing or decreasing there is a downward trend between 1956 and 1980. Could reflect social, political and military issues during this period and voter apathy and/or other distractions. Also this would be more appropriate on a p chart rather than XmR. The denominator should be the number of eligible voters and we should see stair step limits.

    • Thanks for the comments Robert. I agree that this would be a good application for a p-chart. The data I found from the Federal Elections Commission was reported as a percentage so I chose an Individuals chart to convey the “process” of voter turnout. If we had the number of registered voters and the number of those who voted, it might also be interesting to look at a p-prime chart, since the denominator would be so large.

  3. Love to see more use of trend/control charts in the national media. The fact that there are generally accepted trend interpretation standards is unknown to the majority of Americans.

    Note also The Motor Voter Act aka The National Voter Registration Act of 1993 went into effect in 1995 and very likely increased the number of registered voters.

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