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<!ENTITY sect-num '22'>
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<document prev="hints_and_tips.html" id="$Id: glossary.xml 1175606 2011-09-25 22:28:22Z sebb $">

<properties>
  <title>User's Manual: Glossary</title>
</properties>

<body>

<section name="&sect-num;. Glossary" anchor="glossary">

<p>
<a name="Elapsed"><b>Elapsed time</b></a>. JMeter measures the elapsed time from just before sending the request to
just after the last response has been received.
JMeter does not include the time needed to render the response, nor does JMeter process any client code, for example
Javascript.
</p>

<p>
<a name="Latency"><b>Latency</b></a>. JMeter measures the latency from just before sending the request to
just after the first response has been received. Thus the time
includes all the processing needed to assemble the request as well as
assembling the first part of the response, which in general will be longer than one
byte.
Protocol analysers (such as Wireshark) measure the time when bytes are actually sent/received over the interface.
The JMeter time should be closer to that which is experienced by a
browser or other application client.
</p>

<p>
<a name="Median"><b>Median</b></a> is a number which divides the samples into two equal halves.
Half of the samples are smaller than the median, and half are larger.
[Some samples may equal the median.]
This is a standard statistical measure.
See, for example: <a href="http://en.wikipedia.org/wiki/Median">Median</a> entry at Wikipedia.
The Median is the same as the 50<sup>th</sup> Percentile
</p>

<p>
<a name="Percentile"><b>90% Line (90<sup>th</sup> Percentile)</b></a> is the value below which 90% of the samples fall.
The remaining samples too at least as long as the value.
This is a standard statistical measure.
See, for example: <a href="http://en.wikipedia.org/wiki/Percentile">Percentile</a> entry at Wikipedia.
</p>

<p>
<a name="StandardDeviation"><b>Standard Deviation</b></a> is a measure of the variability
of a data set. This is a standard statistical measure.
See, for example: <a href="http://en.wikipedia.org/wiki/Standard_deviation">Standard Deviation</a> entry at Wikipedia.
JMeter calculates the population standard deviation (e.g. STDEVP function in spreadheets), not the sample standard deviation (e.g. STDEV).
</p>

<p>
<a name="ThreadName">The <b>Thread Name</b></a> as it appears in Listeners and logfiles
is derived from the Thread Group name and the thread within the group.<br/>
The name has the format
<code>groupName + " " + groupIndex + "-" + threadIndex</code>
where:
<ul>
<li>groupName - name of the Thread Group element</li>
<li>groupIndex - number of the Thread Group in the Test Plan, starting from 1</li>
<li>threadIndex - number of the thread within the Thread Group, starting from 1</li>
</ul>
A test plan with two Thread Groups each with two threads would use the names:
<pre>
Thread Group 1-1
Thread Group 1-2
Thread Group 2-1
Thread Group 2-2
</pre>
</p>

<p>
<a name="Throughput"><b>Throughput</b></a> is calculated as requests/unit of time.
The time is calculated from the start of the first sample to the end of the last sample.
This includes any intervals between samples, as it is supposed to represent the load on the server.<br/> 
The formula is: Throughput = (number of requests) / (total time).
</p>


</section>

</body>
</document>
