001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.statistics.inference;
018
019/**
020 * Represents an alternative hypothesis for a hypothesis test.
021 *
022 * @see <a href="https://en.wikipedia.org/wiki/Alternative_hypothesis">Alternative hypothesis (Wikipedia)</a>
023 * @since 1.1
024 */
025public enum AlternativeHypothesis {
026    /**
027     * Represents a two-sided test.
028     * <ul>
029     * <li>Null hypothesis (H<sub>0</sub>): {@code p = p0}
030     * <li>Alternative hypothesis (H<sub>1</sub>): {@code p != p0}
031     * </ul>
032     */
033    TWO_SIDED,
034
035    /**
036     * Represents a right-sided test.
037     * <ul>
038     * <li>Null hypothesis (H<sub>0</sub>): {@code p <= p0}
039     * <li>Alternative hypothesis (H<sub>1</sub>): {@code p > p0}
040     * </ul>
041     */
042    GREATER_THAN,
043
044    /**
045     * Represents a left-sided test.
046     * <ul>
047     * <li>Null hypothesis (H<sub>0</sub>): {@code p >= p0}
048     * <li>Alternative hypothesis (H<sub>1</sub>): {@code p < p0}
049     * </ul>
050     */
051    LESS_THAN
052}