A program that causes a computer to implement a correction function, the correction function receiving as first input a first output obtained by performing a first process on sensor data acquired by two or more motion sensors attached to two or more attachment sites of a body and receiving as second input a second output obtained by performing a second process on the sensor data, the correction function correcting (S130, S514, S516, S518) position information included in the first output for the two or more attachment sites to which the motion sensors are attached, wherein the sensor data includes an acceleration in a local coordinate system and an angular velocity in the local coordinate system, wherein the first process includes conversion (S112, S506) of the acceleration in the local coordinate system into acceleration in a global coordinate system and integration (S113, S114, S510) of the acceleration in the global coordinate system, wherein the first output includes the position information in the global coordinate system for the attachment sites obtained by the integration, wherein the second process includes a regression estimation process (S123, S514) of estimating the position information in a body coordinate system for the attachment sites by regression, wherein the regression estimation process (S123, S514) is performed on a basis of the acceleration and the angular velocity in the local coordinate system, wherein the acceleration, after being subjected to a coordinate system conversion from the local coordinate system to the body coordinate system on the basis of the angular velocity, is used as an input to the regression estimation process (S123, S514), the regression estimation process (S123, S514) outputting the second output, the second output including an estimated position information in the body coordinate system, and wherein the correction of the position information included in the first output for the two or more attachment sites to which the motion sensors are attached by the correction function comprises: converting the estimated position information in the body coordinate system into an estimated position information in the global coordinate system on the basis of a result of ground contact detection; and correcting, on the basis of the estimated position information in the global coordinate system, the position information in the global coordinate system for the attachment sites obtained by the integration. wherein the first process includes conversion (S112, S506) of the acceleration in the local coordinate system into acceleration in a global coordinate system and integration (S113, S114, S510) of the acceleration in the global coordinate system, wherein the first output includes the position information in the global coordinate system for the attachment sites obtained by the integration, wherein the second process includes a regression estimation process (S123, S514) of estimating the position information in a body coordinate system for the attachment sites by regression, wherein the regression estimation process (S123, S514) is performed on a basis of the acceleration and the angular velocity in the local coordinate system, wherein the acceleration, after being subjected to a coordinate system conversion from the local coordinate system to the body coordinate system on the basis of the angular velocity, is used as an input to the regression estimation process (S123, S514), the regression estimation process (S123, S514) outputting the second output, the second output including an estimated position information in the body coordinate system, and wherein the correction of the position information included in the first output for the two or more attachment sites to which the motion sensors are attached by the correction function comprises: converting the estimated position information in the body coordinate system into an estimated position information in the global coordinate system on the basis of a result of ground contact detection; and correcting, on the basis of the estimated position information in the global coordinate system, the position information in the global coordinate system for the attachment sites obtained by the integration. converting the estimated position information in the body coordinate system into an estimated position information in the global coordinate system on the basis of a result of ground contact detection; and correcting, on the basis of the estimated position information in the global coordinate system, the position information in the global coordinate system for the attachment sites obtained by the integration.