<p>Should <a href="https://stats.stackexchange.com/questions/tagged/validity" class="post-tag" title="show questions tagged &#39;validity&#39;" rel="tag">validity</a> and <a href="https://stats.stackexchange.com/questions/tagged/validation" class="post-tag" title="show questions tagged &#39;validation&#39;" rel="tag">validation</a> be synonyms, or there is a difference in meaning between them?</p>

<p>So far (07th, July, 2013):<br>
<a href="https://stats.stackexchange.com/questions/tagged/validity" class="post-tag" title="show questions tagged &#39;validity&#39;" rel="tag">validity</a> was used 16 times on CV and <a href="https://stats.stackexchange.com/questions/tagged/validation" class="post-tag" title="show questions tagged &#39;validation&#39;" rel="tag">validation</a> 69 times.</p>

<p>Edit 1:</p>

<p>This is a first suggestion for tag wiki excerpt given the answers of @gung and @Glen_b.</p>

<p><s><strong>Validity</strong> is the extent to which a concept, conclusion or measurement is well-founded and corresponds accurately to the real world. The validity of a measurement tool is considered to be the degree to which the tool measures what it claims to measure.</s> DO NOT use this tag for "validation" model purposes.</p>

<p><strong>Validation</strong> is the process of deciding whether the numerical results quantifying hypothesized relationships between variables, obtained from regression analysis, are in fact acceptable as descriptions of the data. <s> DO NOT use this tag for asking if it is valid ("validity") to use a certain test, measurement or analysis. </s></p>

<p>References: <a href="http://en.wikipedia.org/wiki/Validity_(statistics)" rel="nofollow noreferrer">Wikipedia 1</a>, <a href="http://en.wikipedia.org/wiki/Regression_model_validation" rel="nofollow noreferrer">Wikipedia 2</a></p>

<p><s> Please, manifest the suggestion with upvotes, downvotes, additional comments, additional answers (we have right now 17-July-2013: question -1, @gung +9, Glen_b +6). </s></p>

<p>Edit 2 (status-completed):</p>

<p>The tag wiki excerpts were edited and approved according to modifications suggested by @gung and @Glen_b. See them <a href="https://stats.stackexchange.com/questions/tagged/validity">here</a> and <a href="https://stats.stackexchange.com/questions/tagged/validation">here</a>.<br>
Further improvements can be suggested directly on the tag wiki excerpts pages or with the opening of a new thread.  </p>

<p>Thank's.</p>
