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--- pe:r-lang [2019/04/19 09:40]
218.186.146.102
+++ pe:r-lang [2020/03/24 02:34] (current)
@@ Line 5: / Line 5: @@
   * Use the library
+<code rsplus>
   library(tidyr)
   getwd()
@@ Line 19: / Line 20: @@
   hist(vsltime$time, main="Anastomosis time (all) 2013-2014 n=512")
+</code>
 {{:pe:vsl_success.png?200|}}
 Histogram to check shape of distribution --> looks skewed to the right
+<code rsplus>
   > shapiro.test(vsltime$time)
@@ Line 29: / Line 33: @@
   data:  vsltime$time
   W = 0.91157, p-value = 1.388e-14
+</code>
 Shapiro-Wilk test for normality --> not normal distribution
+<code rsplus>
   > hist(vsl$success)
+</code>
 {{:pe:vsl_success.png?200|}}
+<code rsplus>
   > shapiro.test(vsl$success)
         Shapiro-Wilk normality test
   data:  vsl$success
   W = 0.9117, p-value = 0.0002277
+</code>
+Some other analyses:
+<code rsplus>
+  > plot(vsl$exp,vsl$rate,main="Anastomosis success rate vs experience (in years)")
+  > plot(vsl$exp,vsl$totnum)
+  > plot(vsl$exp,((vsl$totnum/8)+(vsl$rate))/2)
+</code>
+{{:pe:successrate_number_vs_exp.png?400|}}
+Suggests that the first few years of experience does not seem to make a difference to performance, but many years of experience does (? self-selection or already some training). //Some form of correlation analysis might be helpful here.//
+===Spread===
+<code rsplus>
+  > stem(((vsl$totnum/8)+(vsl$rate))/2)
+  The decimal point is 1 digit(s) to the left of the |
+| 5
+|
+|
+|
+| 1333
+| 1111111111112559999999999
+| 1111177777888888888888888
+| 44444444
+| 0
+  > stem(vsl$rate)
+  The decimal point is 1 digit(s) to the left of the |
+| 0
+|
+| 00007
+| 07777771111155555
+| 0000003333366666888
+| 0000000000000000000000
+</code>
+See also [[r:20190423|Combined 13-14]]
+====Sources====
+  * http://www.sthda.com/english/wiki/normality-test-in-r
+  * https://www.rdocumentation.org/packages/graphics/versions/3.5.3/topics/hist
+  * Using subset to drop columns: https://www.listendata.com/2015/06/r-keep-drop-columns-from-data-frame.html
+  * https://www.rdocumentation.org/packages/tidyr/versions/0.8.3/topics/unite
+  * http://www.r-tutor.com/r-introduction/data-frame/data-import
+  * https://www.rdocumentation.org/packages/tidyr/versions/0.8.3
+  * https://uc-r.github.io/tidyr

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