A data analyzer stores data values at any one of N stages while associating the data values with a plurality of data elements respectively and stores association weighting information among the data elements, selects one of the data elements as a target data at random and computes an input stimulus value concerned with the target data on the basis of the association weighting information between the target data and the other data elements and the data values of the other data elements, and updates the data value of the target data on the basis of the computed input stimulus value in such a manner that a threshold decided in accordance with a current data value associated with the target data and varying according to each data value is compared with the input stimulus value to determine whether the data value needs to be changed or not, and that the data value is updated when a decision is made that the data value needs to be changed.