A generation method performed by a computer, the method comprising: obtaining detection results of a target at a plurality of time points by three or more sensors; specifying a share number indicating a number of times of a time point when the target is detected at a same time point among the plurality of time points by each set of two sensors; among the three or more sensors; on a basis of whether each of the three or more sensors; has detected the target at each time point; generating a target share number graph in which the share number is a weight of an edge; generating a sensor connectivity graph obtained by leaving the edge having the weight that is a predetermined number or more from the target share number graph, wherein a set of nodes connected in the sensor connectivity graph indicates a set of sensors in which the number of times the target is observed at the same time point is a predetermined number or more; the method characterized by calculating a variance σ of positions of the target at the plurality of time points observed by the set of two sensors at time points, setting a logarithmic function of the variance σ as the weight of each edge; reflecting the variance σ of the targets as a sensor in the sensor connectivity graph; specifying a path that minimizes the sum of the edges; and specifying the order of the sensors to be selected when calculating external parameters on the basis of the specified path; wherein an order of the sensors in which the variance of the positions of the target becomes as large as possible is specified so that the calculation of the external parameters of the sensors becomes stable. obtaining detection results of a target at a plurality of time points by three or more sensors; specifying a share number indicating a number of times of a time point when the target is detected at a same time point among the plurality of time points by each set of two sensors; among the three or more sensors; on a basis of whether each of the three or more sensors; has detected the target at each time point; generating a target share number graph in which the share number is a weight of an edge; generating a sensor connectivity graph obtained by leaving the edge having the weight that is a predetermined number or more from the target share number graph, wherein a set of nodes connected in the sensor connectivity graph indicates a set of sensors in which the number of times the target is observed at the same time point is a predetermined number or more; the method characterized by calculating a variance σ of positions of the target at the plurality of time points observed by the set of two sensors at time points, setting a logarithmic function of the variance σ as the weight of each edge; reflecting the variance σ of the targets as a sensor in the sensor connectivity graph; specifying a path that minimizes the sum of the edges; and specifying the order of the sensors to be selected when calculating external parameters on the basis of the specified path; wherein an order of the sensors in which the variance of the positions of the target becomes as large as possible is specified so that the calculation of the external parameters of the sensors becomes stable.