GB1160701A - Device for Computing Weighted Moving Averages - Google Patents

Abstract

1,160,701. Weighted moving average computer. BEHAVIOURAL RESEARCH & DEVELOPMENT Ltd. 11 Aug., 1967 [19 July, 1966], No. 32278/66. Heading G4G. A device for computing a weighted moving average given by P n = 1 - w) P n - 1 + wr n , where P n is the weighted moving average incorporating a discrete response r n to an event. P n - 1 is the weighted moving average preceding the response r n and w is a weighting factor; in which P n represents e.g. a performance level for a response r n = 1 for a correct and = 0 for an incorrect result of a test e.g. in the operation of a teaching machine disclosed in 1,160,702; comprises a capacitor C shunted by an electrostatic voltmeter V measuring the voltage on the capacitor, representing the weighted moving average P n - i. On arrival of a response r n to an event (which may be 0 or 1), switch B is closed for a given time to allow the capacitor to discharge by a proportion w of its original voltage through resistor R, and switch A is then closed for an input response 1 to allow current from source S to charge the capacitor by a value proportional to w times the input response; the switch remaining closed for an input 0. The cycle is repeated for each further incoming response, and the voltmeter V shows the weighted moving average continuously. In a modification (Fig. 2, not shown) resistor R is replaced by a second capacitor of value w times that of previously discharged capacitor C, alternately switched in parallel therewith for each operating cycle to absorb w times the charge thereof and then discharged. W may be e.g. #0À1.