1. A method for detecting a difference among a plurality of observation results, comprising: acquiring, by an acquisition unit in a diagnosis system, the diagnosis system running on one or more processors, a first time-series data including a first plurality of observed values by observing a first observation subject over a first passage of time; acquiring, by the acquisition unit in the diagnosis system, a second time-series data including a second plurality of observed values by observing a second observation target over a second passage of time; extracting, by a replication unit in the diagnosis system, a first replicated plurality of observed values from the first time-series data by repeatedly sampling the first plurality of observed values; generating, by the replication unit in the diagnosis system, a replicated first time-series data from the first replicated plurality of observed values; extracting, by the replication unit in the diagnosis system, a second replicated plurality of observed values from the second time-series data by repeatedly sampling the second plurality of observed values; generating, by the replication unit in the diagnosis system, a replicated second time-series data from the second replicated plurality of observed values; calculating, by the calculation unit in the diagnosis system, an index value indicating a difference between the first time-series data and the second time-series data, based upon a difference between first probability values in a first cumulative probability distribution of the first replicated time-series data and second probability values in a second cumulative probability distribution of the second replicated time-series data, wherein the index value is calculated for observed values common to both the first replicated time-series data and the second replicated time-series data; calculating, by a judgment unit in the diagnosis system, a tolerance based on a difference between the calculated index value and a previously calculated index value; and if the tolerance is larger than a reference value, calculating, by the diagnosis system, a new index value by resampling with replacement the first plurality of observed values and the second plurality of observed values including increasing a number of times of repetition of the resampling.