Chi Squared per Degrees of Freedom is a measurement of how accurately a graph's trendline represents the trend of the graph's data points (Matis, Personal interview).
Ideally, this value should be equal to one. A value too high or too low indicates that the fitted trendline does not perfectly represent the graph's data points (Wikipedia, "Reduced chi-squared statistic").
X^2 = Chi Squared.
O = The value of the dependent variable that was collected as raw data (the y value).
C = The value of the dependent variable according to the trendline's equation. (To obtain this value, calculate the y value of the trendline at the x-coordinate where the O value was taken).
σ = The margin of error (see next section).
m = The total number of data points in the set.
*NOTE: This form of calculating error is SPECIFIC to measuring the statistical error of a rate of counts and is NOT UNIVERSAL.
N = The total number of counts.
T = The total time in which data was collected.
V = The degree of freedom.
m = The total number of data points in the set.
F = The number of fit parameters. (The number of fit parameters is equal to the number of terms on the "________" side of the equation y = ________. In short, the number of terms on the side containing the x variable (assuming that the y term is isolated on the opposite side of the equation as all other terms)) (Matis, Personal interview).
Matis, Howard, Ph.D. Personal interview. 20 March 2019.
"Reduced chi-squared statistic." Wikipedia, the free encyclopedia. Accessed 29 March 2018. https://en.wikipedia.org/wiki/Reduced_chi-squared_statistic.