When independent Bernoulli trials become numerous and their success probability decreases with fixed, the count of successes approaches a Poisson distribution. The mean count stays fixed while individual events become rare.当独立伯努利试验次数增加、成功概率减小，并保持 不变时，成功次数趋近于泊松分布。平均次数保持不变，而单次事件越来越罕见。
Green bars show for increasing ; gold dots mark . Horizontal positions are integer event counts, not continuous measurements.绿色柱表示 逐渐增大时的 ，金色点表示 。横向位置是整数事件次数，不是连续测量值。