{"id":710,"date":"2016-05-03T14:42:06","date_gmt":"2016-05-03T20:42:06","guid":{"rendered":"https:\/\/www.qimacros.com\/lean-six-sigma-blog\/?p=710"},"modified":"2019-08-02T11:24:26","modified_gmt":"2019-08-02T17:24:26","slug":"binomial-poisson-attribute-continuous-data-control-chart-confusion","status":"publish","type":"post","link":"https:\/\/www.qimacros.com\/lean-six-sigma-blog\/binomial-poisson-attribute-continuous-data-control-chart-confusion\/","title":{"rendered":"Binomial, Poisson, Attribute, Continuous Data Control Chart Confusion"},"content":{"rendered":"<p>A customer called today confused about\u00a0her data. She wanted to <a href=\"https:\/\/www.qimacros.com\/control-chart\/\">draw a control chart<\/a> and thought the data might have a\u00a0binomial or poisson distribution. She thought it was attribute data. She&#8217;d used the QI Macros Control Chart Wizard to create a control chart of her data and it chose an XmR chart. She wasn&#8217;t sure that was right. When I asked her what kind of data she had, she said, &#8220;write-offs&#8221;.<\/p>\n<p>Write-offs are money, plain and simple. Money is variable (a.k.a. continuous or measured) data.<\/p>\n<p>I explained that to her and suggested she stop worrying about what kind of\u00a0distribution she has and just look at her data.<\/p>\n<ul>\n<li>Decimal data has to be variable\/continuous\/measured (e.g., 7.45, $27.95, 9.5%)<br \/>\nIf you have a single column or row of decimal data use the XmR Chart.<\/li>\n<li>Integer data can be attribute (defects) or variable (days). Examples: 12 defects or 12 days.<br \/>\nIf it&#8217;s\u00a0<em>time<\/em>, use the XmR Chart.<\/li>\n<li>Integers with a Numerator\/Denominator means that you will need either a <em>p<\/em> or a <em>u<\/em> chart. Example: 2\/100 widgets.<br \/>\nIf the data is good\/bad (binomial) use a\u00a0<em>p<\/em> chart.<br \/>\nIf you can have more than one defect per unit\u00a0use\u00a0a\u00a0<em>u<\/em> chart.<br \/>\nIf the denominator\u00a0is a constant size, use an\u00a0<em>np<\/em> chart.<br \/>\nYou can also covert the numerator\/denominator to a ratio (e.g., 2\/100 = 0.02 = 2%) and plot it as an XmR Chart. I personally find it easier to explain an XmR chart to a management team than a\u00a0<em>p\u00a0<\/em>or\u00a0<em>u<\/em> chart with varying control limits. They get lost in why the limits vary and stop looking at the data.<\/li>\n<li>Integer data of unlikely events (e.g., injuries) would be a\u00a0<em>c chart<\/em>.<\/li>\n<\/ul>\n<p>You don&#8217;t need to know anything about distributions to start drawing your first control charts. You just need to know if it is decimals or integers.<\/p>\n<p>Let\u00a0the QI Macros Control Chart Wizard to do this for you auomatically.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>A customer called today confused about&nbsp;her data. She wanted to draw a control chart and thought the data might have a&nbsp;binomial or poisson distribution. She thought it was attribute data. She&rsquo;d used the QI Macros Control Chart Wizard to create a control chart of her data and it chose an XmR chart. She wasn&rsquo;t sure [&hellip;]<\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5,7],"tags":[189,439,190],"class_list":["post-710","post","type-post","status-publish","format-standard","hentry","category-qi-macros","category-six-sigma","tag-binomial","tag-control-charts","tag-poisson"],"_links":{"self":[{"href":"https:\/\/www.qimacros.com\/lean-six-sigma-blog\/wp-json\/wp\/v2\/posts\/710","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.qimacros.com\/lean-six-sigma-blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.qimacros.com\/lean-six-sigma-blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.qimacros.com\/lean-six-sigma-blog\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.qimacros.com\/lean-six-sigma-blog\/wp-json\/wp\/v2\/comments?post=710"}],"version-history":[{"count":4,"href":"https:\/\/www.qimacros.com\/lean-six-sigma-blog\/wp-json\/wp\/v2\/posts\/710\/revisions"}],"predecessor-version":[{"id":2360,"href":"https:\/\/www.qimacros.com\/lean-six-sigma-blog\/wp-json\/wp\/v2\/posts\/710\/revisions\/2360"}],"wp:attachment":[{"href":"https:\/\/www.qimacros.com\/lean-six-sigma-blog\/wp-json\/wp\/v2\/media?parent=710"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.qimacros.com\/lean-six-sigma-blog\/wp-json\/wp\/v2\/categories?post=710"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.qimacros.com\/lean-six-sigma-blog\/wp-json\/wp\/v2\/tags?post=710"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}