System and method for forecasting intermittent demand
First Claim
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1. A computerized method for forecasting intermittent demand for a lead time, comprising the steps of:
 providing a data set of intermittent data comprising a predetermined number of historical demand values;
calculating lead time demand values for the lead time, wherein the calculating step comprises the step of sampling values from the historical demand values;
summing the lead time demand values to provide a lead time demand sum; and
repeating the calculating and summing steps a predetermined number of times to provide a distribution of lead time demand sums that forecast intermittent demand for inventory requirements.
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Abstract
A system and method for forecasting intermittent demand. The forecasting technique utilizes sample reuse techniques to build a distribution of predicted cumulative lead time demand values that can be analyzed using statistical methods, be used as input for an inventory control system, be used as input for a sales planning system, etc.
222 Citations
46 Claims

1. A computerized method for forecasting intermittent demand for a lead time, comprising the steps of:

providing a data set of intermittent data comprising a predetermined number of historical demand values;
calculating lead time demand values for the lead time, wherein the calculating step comprises the step of sampling values from the historical demand values;
summing the lead time demand values to provide a lead time demand sum; and
repeating the calculating and summing steps a predetermined number of times to provide a distribution of lead time demand sums that forecast intermittent demand for inventory requirements.  View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)


8. The method of claim 7, wherein if S≦
 0, then S is forced to LTV.

9. The method of claim 1, further comprising the step of inputting the distribution into an inventory control system.

10. A program product, having a computer usable medium having computer readable code embodied therein that, when executed, comprises:

means for examining intermittent data comprised of a predetermined number of historical demand values made up of zero and nonzero values;
means for calculating lead time demand values for the lead time, wherein the calculating means samples values from the historical demand values;
means for summing the lead time demand values to provide a lead time demand sum;
looping means for generating a plurality of lead time demand sums;
storing means for storing the plurality of lead time demand sums; and
means for providing the plurality of lead time demand sums that forecast inventory requirements.  View Dependent Claims (11, 12, 13, 14, 15)
means for determining if each lead time value to be calculated is zero or nonzero;
means for randomly assigning one of the nonzero historical demand values to each nonzero lead time value; and
means for jittering each nonzero lead time value. 

12. The program product of claim 11, wherein the means for determining if each lead time value to be calculated is zero or nonzero utilizes a Markov model.

13. The program product of claim 11, wherein the jittering means chooses a randomly selected integer that neighbors each nonzero lead time value.

14. The program product of claim 10, further comprising an inventory control means that receives as input the plurality of lead time demand sums.

15. The program product of claim 10, wherein the looping means loops N times, wherein N is a user defined value.

16. A computer system, comprising:

a processing unit;
a computer system memory accessible to the processing unit;
a data set comprising intermittent data stored within the computer system memory, wherein the intermittent data is comprised of a plurality of time series values;
a mechanism for examining the intermittent data; and
a mechanism for generating a plurality of series of lead time demand values, wherein each series of lead time demand values is based upon at least one sampling selection from among the time series values.  View Dependent Claims (17, 18, 19, 20, 21, 22)
a mechanism for summing the lead time demand values within each series of lead time demand values to provide a plurality of lead time demand sums; and
a mechanism for statistically analyzing the plurality of lead time demand sums. 

18. The computer system of claim 16, wherein the generating mechanism determines if a next lead time demand value to be calculated is zero or nonzero.

19. The computer system of claim 18, wherein the generating mechanism randomly assigns a nonzero one of the plurality of time series values to the next lead time demand value if the next lead time demand value is calculated as nonzero.

20. The computer system of claim 16, wherein the generating mechanism comprises a jittering mechanism for altering lead time demand values to neighboring integer values.

21. The computer system of claim 16, wherein the at least one sampling selection randomly selects a single nonzero value.

22. The computer system of claim 16, wherein the at least one sampling selection selects a consecutive series of values.

23. A computerized method for generating a lead time demand (LTD) distribution for a lead time, comprising the steps of:

providing a data set of intermittent data comprising a predetermined number of historical demand values;
calculating subseries sums for the lead time based on the data set of intermittent data;
providing a cumulative distribution function (CDF);
calculating the LTD distribution based on the CDF and subseries sums; and
providing the LTD distribution to manage product requirements.  View Dependent Claims (24, 25, 26, 27, 28)


29. A program product embodied on a computer usable medium, for generating a lead time demand (LTD) distribution, wherein said program product, when executed, comprises:

means for examining a data set of intermittent data comprising a predetermined number of historical demand values;
means for calculating subseries sums based on the data set of intermittent data;
means for calculating the LTD distribution based on a cumulative distribution function (CDF) and the subseries sums; and
means for providing the LTD distribution to manage product requirements.  View Dependent Claims (30, 31, 32, 33, 34, 35)


33. The program product of claim 29, wherein the CDF is parametric and is given as:

34. The program product of claim 33, wherein G{circumflex over ( )}(X) is estimated by integrating g(X) from −
 ∞
to X, where
 ∞

35. The program product of claim 33, wherein G{circumflex over ( )}(X) is estimated by integrating g(X) from −
 ∞
to X, where
 ∞

36. An inventory management program product embodied on a computer usable medium, that, when executed, comprises:

a forecast mechanism, the forecast mechanism including;
,means for examining intermittent data comprised of a predetermined number of historical demand values made up of zero and nonzero values;
means for calculating lead time demand values for a lead time, wherein the calculating means samples values from the historical demand values;
means for summing the lead time demand values to provide a lead time demand sum;
looping means for generating a plurality of lead time demand sums; and
storing means for storing the plurality of lead time demand sums on a computer system memory; and
an inventory control mechanism, including;
means for reading the plurality of lead time demand sums; and
means for outputting inventory reorder information that specifies when a product order should be placed.  View Dependent Claims (37, 38, 39, 40, 41)
means for determining if each lead time value to be calculated is zero or nonzero;
means for randomly assigning one of the nonzero historical demand values to each nonzero lead time value; and
means for jittering each nonzero lead value. 

38. The program product of claim 36, wherein the inventory control mechanism further comprises means for outputting performance measures.

39. The program product of claim 36, wherein the inventory reorder information comprise a reorder point and an order quantity.

40. The program product of claim 36, wherein the inventory reorder information comprises a review interval and an orderupto value.

41. The program product of claim 38, wherein the performance measures include inventory/order costs and service level percentages.

42. An inventory management program product embodied on a computer usable medium, that, when executed, comprises:

a forecast mechanism, the forecast mechanism including;
means for examining a data set of intermittent data comprising a predetermined number of historical demand values;
means for calculating subseries sums based on the data set of intermittent data;
means for calculating a lead time demand (LTD) distribution based on a cumulative distribution function (CDF) and the subseries sums;
an inventory control mechanism, including;
means for reading the plurality of lead time demand sums; and
means for outputting inventory reorder information that specifies when an order should be placed.  View Dependent Claims (43, 44, 45, 46)

1 Specification