--- a/heuristics/dateHeuristics.php
+++ b/heuristics/dateHeuristics.php
@@ -1,4 +1,92 @@
-        - long contract period (number of weeks/days?)
-            - Reported late
-        - 45 days? A late contract is a dodgy contract except maybe for variations?
-
+<?php
+//long contract period (number of weeks/days?)
+$heuristics["DATE_LONG_CONTRACT_PERIOD"] = Array(
+	"description" => "long contract period (number of weeks/days?)"
+);
+function DATE_LONG_CONTRACT_PERIOD($cn)
+{
+	$averageContractPeriod = getAverageContractPeriod();
+	$stddevContractPeriod = getstddevContractPeriod();
+	$diff = strtotime($cn['contractEnd']) - strtotime($cn['contractStart']);
+	$days = intval($diff / (60 * 60 * 24));
+	$value = abs($days - $averageContractPeriod) / $stddevContractPeriod;
+	return Array(
+		"heuristic_value" => $value,
+		"raw_value" => $days,
+		"mean" => $averageContractPeriod,
+		"stddev" => $stddevContractPeriod
+	);
+}
+$averageContractPeriod;
+function getAverageContractPeriod()
+{
+	global $averageContractPeriod;
+	if (!$averageContractPeriod) {
+		$query = "select AVG(dateDiff(contractEnd,contractStart)) from contractnotice";
+		$result = mysql_query($query);
+		$r = mysql_fetch_array($result, MYSQL_BOTH);
+		$averageContractPeriod = $r[0];
+	}
+	return $averageContractPeriod;
+}
+$stddevContractPeriod;
+function getstddevContractPeriod()
+{
+	global $stddevContractPeriod;
+	if (!$stddevContractPeriod) {
+		$query = "select STDDEV(dateDiff(contractEnd,contractStart)) from contractnotice";
+		$result = mysql_query($query);
+		$r = mysql_fetch_array($result, MYSQL_BOTH);
+		$stddevContractPeriod = $r[0];
+	}
+	return $stddevContractPeriod;
+}
+//Reported late, 45 days? A late contract is a dodgy contract except maybe for variations?
+$heuristics["DATE_REPORTED_LATE"] = Array(
+	"description" => "Reported late, 45 days?"
+);
+function DATE_REPORTED_LATE($cn)
+{
+	$averageDaysLate = getAverageDaysLate();
+	$stddevDaysLate = getStddevDaysLate();
+	$diff = strtotime($cn['publishDate']) - strtotime($cn['contractStart']);
+	$days = intval($diff / (60 * 60 * 24));
+	if ($days <= 0) {
+		$value = 0;
+	}
+	else {
+		// +1 demerit for exceeding 45 day requirement
+		$value = (abs($days - $averageDaysLate) / $stddevDaysLate) + ($days < 45 ? 0 : 1);
+	}
+	return Array(
+		"heuristic_value" => $value,
+		"raw_value" => $days,
+		"mean" => $averageDaysLate,
+		"stddev" => $stddevDaysLate
+	);
+}
+$averageDaysLate;
+function getAverageDaysLate()
+{
+	global $averageDaysLate;
+	if (!$averageDaysLate) {
+		$query = "select AVG(dateDiff(publishDate,contractStart)) from contractnotice";
+		$result = mysql_query($query);
+		$r = mysql_fetch_array($result, MYSQL_BOTH);
+		$averageDaysLate = $r[0];
+	}
+	return $averageDaysLate;
+}
+$stddevDaysLate;
+function getStddevDaysLate()
+{
+	global $stddevDaysLate;
+	if (!$stddevDaysLate) {
+		$query = "select STDDEV(dateDiff(publishDate,contractStart)) from contractnotice";
+		$result = mysql_query($query);
+		$r = mysql_fetch_array($result, MYSQL_BOTH);
+		$stddevDaysLate = $r[0];
+	}
+	return $stddevDaysLate;
+}
+?>