X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=doc%2Ftutorial.texi;h=b76d8bf838ab1b50de389fa346cd39beead8a41d;hb=d678fc2a9b1cfb7a53f3cb4082f6939e3e7f31c6;hp=757a49fbf7b6a4e47fdebba0af84ca558bd66275;hpb=6a38a2cb3ab0e2987e049e761122b1d2a61468a7;p=pspp diff --git a/doc/tutorial.texi b/doc/tutorial.texi index 757a49fbf7..b76d8bf838 100644 --- a/doc/tutorial.texi +++ b/doc/tutorial.texi @@ -1,3 +1,12 @@ +@c PSPP - a program for statistical analysis. +@c Copyright (C) 2017 Free Software Foundation, Inc. +@c Permission is granted to copy, distribute and/or modify this document +@c under the terms of the GNU Free Documentation License, Version 1.3 +@c or any later version published by the Free Software Foundation; +@c with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. +@c A copy of the license is included in the section entitled "GNU +@c Free Documentation License". +@c @alias prompt = sansserif @include tut.texi @@ -492,14 +501,14 @@ A sensible check to perform on survey data is the calculation of reliability. This gives the statistician some confidence that the questionnaires have been completed thoughtfully. -If you examine the labels of variables @var{v1}, @var{v3} and @var{v5}, +If you examine the labels of variables @var{v1}, @var{v3} and @var{v4}, you will notice that they ask very similar questions. One would therefore expect the values of these variables (after recoding) to closely follow one another, and we can test that with the @cmd{RELIABILITY} command (@pxref{RELIABILITY}). @ref{reliability} shows a @pspp{} session where the user (after recoding negatively scaled variables) requests reliability statistics for -@var{v1}, @var{v3} and @var{v5}. +@var{v1}, @var{v3} and @var{v4}. @float Example, reliability @cartouche @@ -509,7 +518,7 @@ negatively scaled variables) requests reliability statistics for @prompt{PSPP>} * recode negatively worded questions. @prompt{PSPP>} compute v3 = 6 - v3. @prompt{PSPP>} compute v5 = 6 - v5. -@prompt{PSPP>} reliability v1, v3, v5. +@prompt{PSPP>} reliability v1, v3, v4. @end example Output (dictionary information omitted for clarity): @@ -527,19 +536,19 @@ Output (dictionary information omitted for clarity): #================#==========# #Cronbach's Alpha#N of Items# #================#==========# -# .86# 3# +# .81# 3# #================#==========# @end example @end cartouche @caption{Recoding negatively scaled variables, and testing for reliability with the @cmd{RELIABILITY} command. The Cronbach Alpha coefficient suggests a high degree of reliability among variables -@var{v1}, @var{v2} and @var{v5}.} +@var{v1}, @var{v3} and @var{v4}.} @end float As a rule of thumb, many statisticians consider a value of Cronbach's Alpha of 0.7 or higher to indicate reliable data. -Here, the value is 0.86 so the data and the recoding that we performed +Here, the value is 0.81 so the data and the recoding that we performed are vindicated.