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Business / Finance / Markets / Money

Three Graphs and a Regression Equation

Three Graphs and a Regression Equation

And we are less than one-third of the way through November.

Cumulative casualties seem to be rising at a faster and faster pace.


Figure 1: Cumulative mass shooting fatalities (dark red), non-fatal injured (pink), from 1982M08, through November 8, 2018.. Orange denotes 2017M01-2018M11, light orange 2016M11-2017M01. Source: Mother Jones, accessed 11/8/2018, and author’s calculations.

The frequency of mass shooting events seems to be increasing. A negative binomial count regression (estimated using QML) indicates 1.6 more events per month under Trump (estimate statistically significant a 1% msl).


Figure 2: Mass shooting event count, from 1982M08, through November 8, 2018.. Orange denotes 2017M01-2018M11, light orange 2016M11-2017M01. Source: Mother Jones, accessed 11/8/2018, and author’s calculations.

Fatalities are increasing over the Trump era.

Figure 3: Mass shooting fatalities, from 1982M08, through November 8, 2018. Orange denotes 2017Q1-2018Q4, light orange 2016Q4-2017Q1. Source: Mother Jones, accessed 11/8/2018, and author’s calculations.

Regression 1982q4-2018q4:

f = -6.19 + 0.028pop + 5.590trump

Adj.R2 = 0.21, N = 145, DW = 2.09, bold denotes significance at 10% msl using HAC robust standard errors.

Where f denotes mass shooting fatalities, pop is population in millions, trump is a dummy variable for Trump administration.

One can interpret this as follows: a Trump administration quarter is associated with 5.6 greater fatalities from mass shootings, or 22.4 on an annualized basis. (Over 1982q4-16q4, the average fatalities per quarter is 4.876). Inclusion of a deterministic time trend yields a negative coefficient on population, and a trump coefficient (4.464) significant at 6% msl.

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