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--- en:create:functions:valuemean [21.01.2015 12:35] – [valueMean()] alexander.ritter
+++ en:create:functions:valuemean [14.03.2022 12:02] (current) – walliser
@@ Line 13: / Line 13: @@
   * //variables// -- A list (array) of variable IDs as stated in the **Variables Overview**
-**Note** This works in the same way as ''[[:en:create:functions:valuesum|valueSum()]]'' -- the parameters are described in detail in this chapter with various examples.
+**Note** This works in the same way as ''[[:en:create:functions:valuesum|valueSum()]]'' -- the parameters are described in this chapter in detail with various examples.
-===== Example =====
+===== Example filter =====
 In the following example, question "AB02" will be displayed if the mean in the scale "AB01" is at least 1.5.
@@ Line 27: / Line 27: @@
 }
 </code>
+===== Example items =====
+The following PHP code calculates the mean of the items 2, 4, 6, 8 and 10 in question AB02.
+<code php>
+valueMean('AB01', [2, 4, 6, 8, 10])
+</code>
+===== Example variables =====
+The following PHP code calculates the mean of the variables AB03_01, AB03_02, BB01_02 and BB01_04.
+<code php>
+valueMean(['AB03_01', 'AB03_02', 'BB01_02', 'BB01_04'])
+</code>
+Whether a [[:de:create:array|Array]] is defined in one line or over several lines is irrelevant for the function, but can improve clarity.
+<code php>
+valueMean([
+    'AB03_01', 'AB03_02',
+    'BB01_02', 'BB01_04'
+])
+</code>
+===== Example weighting =====
+It is not possible to calculate a weighted average using "valueMean()", but using a FOR loop and simple arithmetic operations such a weighted average can be easily calculated using PHP.
+<code php>
+$weights = [
+    'AB03_01' => 1.1,
+    'AB03_02' => 1.4,
+    'BB01_02' => 0.7,
+    'BB01_04' => 0.8
+];
+$sumValue = 0;
+$sumWeight = 0;
+foreach ($weights as $varID => $weight) {
+    $val = (float)value($varID);
+    // Exclude missing data (≤0)
+    if ($val > 0) {
+        $sumValue+= $val * $weight;
+        $sumWeight+= $weight;
+    }
+}
+// Mean = sum divided by count
+if ($sumWeight == 0) {
+  $mean = -1;  // No data
+} else {
+  $mean = $sumValue / $sumWeight;
+}
+</code>