text: /**
  * @license Apache-2.0
  *
  * Copyright (c) 2019 The Stdlib Authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *    http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License 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.
  */
  
  'use strict';
  
  var incrmean = require( '@stdlib/stats/incr/mean' );
  var dataset = require( './../lib' );
  
  function mean( a, b ) {
  	return ( a + b ) / 2.0;
  }
  
  function reldiff( a, b ) {
  	return 100.0 * ( (a-b)/a );
  }
  
  /*
  * GOAL: determine whether people avoid giving birth on the 13th of each month.
  *
  * NOTE: for a more thorough analysis, we'd account for holidays.
  */
  
  // Retrieve the data:
  var data = dataset();
  
  // Initialize arrays for storing births for particular day numbers:
  var d6or20 = [ [], [], [], [], [], [], [] ];
  var d13 = [ [], [], [], [], [], [], [] ];
  
  // Extract the day number data...
  var d;
  var w;
  var i;
  for ( i = 0; i < data.length; i++ ) {
  	d = data[ i ].date_of_month;
  	w = data[ i ].day_of_week;
  	if ( d === 6 ) {
  		// Average of days 6 and 20 for the same month:
  		d6or20[ w-1 ].push( mean( data[ i ].births, data[ i+14 ].births ) );
  	} else if ( d === 13 ) {
  		d13[ w-1 ].push( data[ i ].births );
  	}
  }
  
  // Initialize accumulators for computing the average relative difference...
  var means = [];
  for ( i = 0; i < 7; i++ ) {
  	means.push( incrmean() );
  }
  
  // Compute the average relative difference between days 6/20 with day 13...
  var l1;
  var l2;
  var mu;
  var j;
  for ( i = 0; i < 7; i++ ) {
  	l1 = d13[ i ];
  	l2 = d6or20[ i ];
  	mu = means[ i ];
  	for ( j = 0; j < l1.length; j++ ) {
  		mu( reldiff( l1[ j ], l2[ j ] ) );
  	}
  }
  
  // Print the results...
  for ( i = 0; i < 7; i++ ) {
  	console.log( '%d: %d%', i+1, means[ i ]().toFixed( 3 ) );
  }
  