Parameter-estimation-by-optimization: The number of games played between each no-hitter in the modern era (1901-2015) of Major League Baseball is stored in the array nohitter_times. If we assume that no-hitters are described as a Poisson process, then the time between no-hitters is Exponentially distributed. The Exponential distribution has a single parameter, which we will call To, the typical interval time. The value of the parameter To that makes the exponential distribution best match the data is the mean interval time (where time is in units of number of games) between no-hitters.