System and method for forecasting intermittent demand
DCFirst 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.
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Citations
46 Claims
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1. A computerized method for forecasting intermittent demand for a lead time, comprising the steps of:
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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)
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8. The method of claim 7, wherein if S≦
- 0, then S is forced to LTV.
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9. The method of claim 1, further comprising the step of inputting the distribution into an inventory control system.
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10. A program product, having a computer usable medium having computer readable code embodied therein that, when executed, comprises:
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means for examining intermittent data comprised of a predetermined number of historical demand values made up of zero and non-zero 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 non-zero;
means for randomly assigning one of the non-zero historical demand values to each non-zero lead time value; and
means for jittering each non-zero lead time value.
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12. The program product of claim 11, wherein the means for determining if each lead time value to be calculated is zero or non-zero utilizes a Markov model.
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13. The program product of claim 11, wherein the jittering means chooses a randomly selected integer that neighbors each non-zero lead time value.
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14. The program product of claim 10, further comprising an inventory control means that receives as input the plurality of lead time demand sums.
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15. The program product of claim 10, wherein the looping means loops N times, wherein N is a user defined value.
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16. A computer system, comprising:
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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.
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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 non-zero.
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19. The computer system of claim 18, wherein the generating mechanism randomly assigns a non-zero 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 non-zero.
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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.
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21. The computer system of claim 16, wherein the at least one sampling selection randomly selects a single non-zero value.
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22. The computer system of claim 16, wherein the at least one sampling selection selects a consecutive series of values.
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23. A computerized method for generating a lead time demand (LTD) distribution for a lead time, comprising the steps of:
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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)
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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:
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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)
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33. The program product of claim 29, wherein the CDF is parametric and is given as:
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34. The program product of claim 33, wherein G{circumflex over ( )}(X) is estimated by integrating g(X) from −
- ∞
to X, where
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35. The program product of claim 33, wherein G{circumflex over ( )}(X) is estimated by integrating g(X) from −
- ∞
to X, where
- ∞
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36. An inventory management program product embodied on a computer usable medium, that, when executed, comprises:
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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 non-zero 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 non-zero;
means for randomly assigning one of the non-zero historical demand values to each non-zero lead time value; and
means for jittering each non-zero lead value.
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38. The program product of claim 36, wherein the inventory control mechanism further comprises means for outputting performance measures.
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39. The program product of claim 36, wherein the inventory reorder information comprise a reorder point and an order quantity.
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40. The program product of claim 36, wherein the inventory reorder information comprises a review interval and an order-up-to value.
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41. The program product of claim 38, wherein the performance measures include inventory/order costs and service level percentages.
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42. An inventory management program product embodied on a computer usable medium, that, when executed, comprises:
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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)
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Specification