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Adding Wilson Score Confidence Interval Strategy (#567)
* Configurable RetainCompletenessRule * Add doc string * Add default completeness const * Add ConfidenceIntervalStrategy * Add Separate Wilson and Wald Interval Test * Add License information, Fix formatting * Add License information * formatting fix * Update documentation * Make WaldInterval the default strategy for now * Formatting import to per line * Separate group import to per line import
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55 changes: 55 additions & 0 deletions
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src/main/scala/com/amazon/deequ/suggestions/rules/interval/ConfidenceIntervalStrategy.scala
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| /** | ||
| * Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"). You may not | ||
| * use this file except in compliance with the License. A copy of the License | ||
| * is located at | ||
| * | ||
| * http://aws.amazon.com/apache2.0/ | ||
| * | ||
| * or in the "license" file accompanying this file. This file is distributed on | ||
| * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either | ||
| * express or implied. See the License for the specific language governing | ||
| * permissions and limitations under the License. | ||
| * | ||
| */ | ||
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| package com.amazon.deequ.suggestions.rules.interval | ||
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| import breeze.stats.distributions.{Gaussian, Rand} | ||
| import com.amazon.deequ.suggestions.rules.interval.ConfidenceIntervalStrategy._ | ||
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| /** | ||
| * Strategy for calculate confidence interval | ||
| * */ | ||
| trait ConfidenceIntervalStrategy { | ||
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| /** | ||
| * Generated confidence interval interval | ||
| * @param pHat sample of the population that share a trait | ||
| * @param numRecords overall number of records | ||
| * @param confidence confidence level of method used to estimate the interval. | ||
| * @return | ||
| */ | ||
| def calculateTargetConfidenceInterval( | ||
| pHat: Double, | ||
| numRecords: Long, | ||
| confidence: Double = defaultConfidence | ||
| ): ConfidenceInterval | ||
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| def validateInput(pHat: Double, confidence: Double): Unit = { | ||
| require(0.0 <= pHat && pHat <= 1.0, "pHat must be between 0.0 and 1.0") | ||
| require(0.0 <= confidence && confidence <= 1.0, "confidence must be between 0.0 and 1.0") | ||
| } | ||
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| def calculateZScore(confidence: Double): Double = Gaussian(0, 1)(Rand).inverseCdf(1 - ((1.0 - confidence)/ 2.0)) | ||
| } | ||
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| object ConfidenceIntervalStrategy { | ||
| val defaultConfidence = 0.95 | ||
| val defaultIntervalStrategy: ConfidenceIntervalStrategy = WaldIntervalStrategy() | ||
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| case class ConfidenceInterval(lowerBound: Double, upperBound: Double) | ||
| } | ||
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src/main/scala/com/amazon/deequ/suggestions/rules/interval/WaldIntervalStrategy.scala
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| /** | ||
| * Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"). You may not | ||
| * use this file except in compliance with the License. A copy of the License | ||
| * is located at | ||
| * | ||
| * http://aws.amazon.com/apache2.0/ | ||
| * | ||
| * or in the "license" file accompanying this file. This file is distributed on | ||
| * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either | ||
| * express or implied. See the License for the specific language governing | ||
| * permissions and limitations under the License. | ||
| * | ||
| */ | ||
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| package com.amazon.deequ.suggestions.rules.interval | ||
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| import com.amazon.deequ.suggestions.rules.interval.ConfidenceIntervalStrategy.ConfidenceInterval | ||
| import com.amazon.deequ.suggestions.rules.interval.ConfidenceIntervalStrategy.defaultConfidence | ||
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| import scala.math.BigDecimal.RoundingMode | ||
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| /** | ||
| * Implements the Wald Interval method for creating a binomial proportion confidence interval. Provided for backwards | ||
| * compatibility. using [[WaldIntervalStrategy]] for calculating confidence interval can be problematic when dealing | ||
| * with small sample sizes or proportions close to 0 or 1. It also have poorer coverage and might produce confidence | ||
| * limit outside the range of [0,1] | ||
| * @see <a | ||
| * href="http://en.wikipedia.org/wiki/Binomial_proportion_confidence_interval#Normal_approximation_interval"> | ||
| * Normal approximation interval (Wikipedia)</a> | ||
| */ | ||
| @deprecated("WilsonScoreIntervalStrategy is recommended for calculating confidence interval") | ||
| case class WaldIntervalStrategy() extends ConfidenceIntervalStrategy { | ||
| def calculateTargetConfidenceInterval( | ||
| pHat: Double, | ||
| numRecords: Long, | ||
| confidence: Double = defaultConfidence | ||
| ): ConfidenceInterval = { | ||
| validateInput(pHat, confidence) | ||
| val successRatio = BigDecimal(pHat) | ||
| val marginOfError = BigDecimal(calculateZScore(confidence) * math.sqrt(pHat * (1 - pHat) / numRecords)) | ||
| val lowerBound = (successRatio - marginOfError).setScale(2, RoundingMode.DOWN).toDouble | ||
| val upperBound = (successRatio + marginOfError).setScale(2, RoundingMode.UP).toDouble | ||
| ConfidenceInterval(lowerBound, upperBound) | ||
| } | ||
| } |
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src/main/scala/com/amazon/deequ/suggestions/rules/interval/WilsonScoreIntervalStrategy.scala
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| /** | ||
| * Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"). You may not | ||
| * use this file except in compliance with the License. A copy of the License | ||
| * is located at | ||
| * | ||
| * http://aws.amazon.com/apache2.0/ | ||
| * | ||
| * or in the "license" file accompanying this file. This file is distributed on | ||
| * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either | ||
| * express or implied. See the License for the specific language governing | ||
| * permissions and limitations under the License. | ||
| * | ||
| */ | ||
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| package com.amazon.deequ.suggestions.rules.interval | ||
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| import com.amazon.deequ.suggestions.rules.interval.ConfidenceIntervalStrategy.ConfidenceInterval | ||
| import com.amazon.deequ.suggestions.rules.interval.ConfidenceIntervalStrategy.defaultConfidence | ||
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| import scala.math.BigDecimal.RoundingMode | ||
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| /** | ||
| * Using Wilson score method for creating a binomial proportion confidence interval. | ||
| * | ||
| * @see <a | ||
| * href="http://en.wikipedia.org/wiki/Binomial_proportion_confidence_interval#Wilson_score_interval"> | ||
| * Wilson score interval (Wikipedia)</a> | ||
| */ | ||
| case class WilsonScoreIntervalStrategy() extends ConfidenceIntervalStrategy { | ||
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| def calculateTargetConfidenceInterval( | ||
| pHat: Double, numRecords: Long, | ||
| confidence: Double = defaultConfidence | ||
| ): ConfidenceInterval = { | ||
| validateInput(pHat, confidence) | ||
| val zScore = calculateZScore(confidence) | ||
| val zSquareOverN = math.pow(zScore, 2) / numRecords | ||
| val factor = 1.0 / (1 + zSquareOverN) | ||
| val adjustedSuccessRatio = pHat + zSquareOverN/2 | ||
| val marginOfError = zScore * math.sqrt(pHat * (1 - pHat)/numRecords + zSquareOverN/(4 * numRecords)) | ||
| val lowerBound = BigDecimal(factor * (adjustedSuccessRatio - marginOfError)).setScale(2, RoundingMode.DOWN).toDouble | ||
| val upperBound = BigDecimal(factor * (adjustedSuccessRatio + marginOfError)).setScale(2, RoundingMode.UP).toDouble | ||
| ConfidenceInterval(lowerBound, upperBound) | ||
| } | ||
| } |
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