Detecting change in data
First Claim
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1. A method of detecting a change in data produced by a system, comprising:
- computing, by a processor, predicted data values for plural time points;
receiving, by the processor, actual data values for the plural time points;
computing, by the processor, residual values derived from differences between the predicted data values and actual data values;
calculating centered residual values that are derived from subtracting an aggregate value of the computed residual values from the computed residual values;
determining, based on the centered residual values, a time point at which the change in data occurred, wherein the determining comprises;
computing cumulative sums of the centered residual values, wherein the cumulative sums are at corresponding plural time points; and
comparing the cumulative sums to at least one threshold to determine whether the change in data has occurred; and
indicating that the change in data has occurred in response to at least one of the cumulative sums crossing the at least one threshold, wherein indicating the change in data comprises indicating a systematic change of data produced by a dynamically changing system that produces data exhibiting at least one of non-linear trends, seasonal effects, and heteroscedasticity.
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Abstract
To detect a change in data produced by a system, predicted data values for plural time points are computed. Actual data values for the plural time points are received, and residual values are derived from differences between the predicted data values and actual data values. Based on the computed residual values, a time point at which the change in data occurred is determined.
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Citations
22 Claims
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1. A method of detecting a change in data produced by a system, comprising:
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computing, by a processor, predicted data values for plural time points; receiving, by the processor, actual data values for the plural time points; computing, by the processor, residual values derived from differences between the predicted data values and actual data values; calculating centered residual values that are derived from subtracting an aggregate value of the computed residual values from the computed residual values; determining, based on the centered residual values, a time point at which the change in data occurred, wherein the determining comprises; computing cumulative sums of the centered residual values, wherein the cumulative sums are at corresponding plural time points; and comparing the cumulative sums to at least one threshold to determine whether the change in data has occurred; and indicating that the change in data has occurred in response to at least one of the cumulative sums crossing the at least one threshold, wherein indicating the change in data comprises indicating a systematic change of data produced by a dynamically changing system that produces data exhibiting at least one of non-linear trends, seasonal effects, and heteroscedasticity. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An article comprising at least one machine-readable storage medium containing instructions that when executed cause a processor to:
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compute a time series of cumulative sums based on actual data values contained in an input data set, wherein computing the time series of cumulative sums comprises; computing predicted data values for plural time points; computing residual values derived from differences between the predicted data values and actual data values; calculating centered residual values that are derived from subtracting an aggregate value of the computed residual values from the computed residual values, wherein the cumulative sums are cumulative sums of the centered residual values; compare the cumulative sums in the time series against at least one threshold; and detect a change of the data values in the input data set in response to at least one of the cumulative sums crossing the at least one threshold, wherein detecting the change of the data values in the input data set comprises detecting a systematic change of data values produced by a dynamically changing system that produces data exhibiting at least one of non-linear trends, seasonal effects, and heteroscedasticity. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method comprising:
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generating a predictive model based on an input data set produced by a system; computing, by a processor, predicted data values for plural time points using the predictive model; computing, by the processor, residual values based on the predicted data values and actual data values of the input data set; calculating, by the processor, centered residual values by subtracting an average residual value from corresponding computed residual values; computing, by the processor, a time series of cumulative sums of the centered residual values; comparing, by the processor, the cumulative sums in the time series against at least one threshold; and detecting a change of the data values in the input data set in response to at least one of the cumulative sums crossing the at least one threshold, wherein detecting the change of the data values in the input data set comprises detecting a systematic change of data values produced by a dynamically changing system that produces data exhibiting at least one of non-linear trends, seasonal effects, and heteroscedasticity. - View Dependent Claims (16, 17)
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18. A system comprising:
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a processor; and a detection module executable on the processor to detect a change in data by; calculating a time series of predicted data values; receiving a time series of actual data values; calculating residual values based on differences between the predicted data values and actual data values; calculating centered residual values that are derived from subtracting an aggregate value of the calculated residual values from the calculated residual values; determining, based on the centered residual values, occurrence of the change in data, wherein the detection module determines occurrence of the change in data by; computing a time series of cumulative sums of the centered residual values, wherein the computed cumulative sums are at corresponding time points; and comparing the cumulative sums to at least one threshold to determine whether the change in data has occurred; and wherein the detection module is executable to indicate that the change in data has occurred in response to at least one of the cumulative sums crossing the at least one threshold, wherein indicating the change in data comprises indicating a systematic change of data produced by a dynamically changing system that produces data exhibiting at least one of non-linear trends, seasonal effects, and heteroscedasticity. - View Dependent Claims (19)
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20. A method of detecting a change in an input data set produced by a system, comprising:
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computing, by a processor, a time series of cumulative sums based on actual data values contained in the input data set produced by the system, wherein computing the time series of cumulative sums comprises; computing predicted data values for plural time points; computing residual values derived from differences between the predicted data values and actual data values; calculating centered residual values that are derived from subtracting an aggregate value of the computed residual values from the computed residual values, wherein the cumulative sums are cumulative sums of the centered residual values; comparing, by the processor, the cumulative sums in the time series against at least one threshold; and detecting a change of the data values in the input data set in response to at least one of the cumulative sums crossing the at least one threshold, wherein detecting the change of the data values in the input data set comprises detecting a systematic change of data values produced by a dynamically changing system that produces data exhibiting at least one of non-linear trends, seasonal effects, and heteroscedasticity. - View Dependent Claims (21, 22)
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Specification