The Visual Display of Likert Data
The Likert scale was first introduced by Rensis Likert in 1932 (Likert1932?) and has become a widely used for assessment and survey designs.
data(pisaitems)
items24 <- pisaitems[,substr(names(pisaitems), 1,5) == 'ST24Q']
head(items24); ncol(items24)
#> ST24Q01 ST24Q02 ST24Q03 ST24Q04
#> 68038 Disagree Strongly agree Strongly agree Strongly disagree
#> 68039 Agree Strongly disagree Strongly disagree Strongly agree
#> 68040 Strongly agree Strongly disagree Strongly disagree Agree
#> 68041 Disagree Disagree Agree Strongly disagree
#> 68042 Strongly disagree Disagree Strongly disagree Disagree
#> 68043 Agree Strongly disagree Strongly disagree Agree
#> ST24Q05 ST24Q06 ST24Q07 ST24Q08
#> 68038 Strongly agree Strongly disagree Agree Disagree
#> 68039 Strongly disagree Agree Strongly disagree Agree
#> 68040 Strongly disagree Strongly agree Strongly disagree Agree
#> 68041 Disagree Disagree Agree Strongly disagree
#> 68042 Strongly disagree Disagree Disagree Agree
#> 68043 Strongly disagree Agree Strongly disagree Agree
#> ST24Q09 ST24Q10 ST24Q11
#> 68038 Strongly disagree Agree Agree
#> 68039 Strongly agree Strongly disagree Strongly disagree
#> 68040 Disagree Disagree Strongly disagree
#> 68041 Strongly disagree Agree Agree
#> 68042 Agree Agree Strongly disagree
#> 68043 Strongly agree Strongly disagree Strongly disagree
#> [1] 11
names(items24) <- c(
ST24Q01="I read only if I have to.",
ST24Q02="Reading is one of my favorite hobbies.",
ST24Q03="I like talking about books with other people.",
ST24Q04="I find it hard to finish books.",
ST24Q05="I feel happy if I receive a book as a present.",
ST24Q06="For me, reading is a waste of time.",
ST24Q07="I enjoy going to a bookstore or a library.",
ST24Q08="I read only to get information that I need.",
ST24Q09="I cannot sit still and read for more than a few minutes.",
ST24Q10="I like to express my opinions about books I have read.",
ST24Q11="I like to exchange books with my friends.")l24 <- likert(items24)
l24
#> Item Strongly disagree
#> 1 I read only if I have to. 22.82298
#> 2 Reading is one of my favorite hobbies. 20.32308
#> 3 I like talking about books with other people. 21.24927
#> 4 I find it hard to finish books. 24.95877
#> 5 I feel happy if I receive a book as a present. 19.28187
#> 6 For me, reading is a waste of time. 42.24040
#> 7 I enjoy going to a bookstore or a library. 17.84124
#> 8 I read only to get information that I need. 14.98106
#> 9 I cannot sit still and read for more than a few minutes. 33.11719
#> 10 I like to express my opinions about books I have read. 13.53650
#> 11 I like to exchange books with my friends. 22.51850
#> Disagree Agree Strongly agree
#> 1 35.90570 30.53855 10.732772
#> 2 36.32162 31.93453 11.420770
#> 3 33.74201 35.96325 9.045464
#> 4 40.39249 26.50886 8.139890
#> 5 27.65288 40.17350 12.891747
#> 6 40.64689 10.97568 6.137024
#> 7 33.37107 36.88333 11.904361
#> 8 35.41769 35.75990 13.841359
#> 9 43.12805 16.91875 6.836012
#> 10 27.53867 43.82185 15.102982
#> 11 33.02265 32.07993 12.378918summary(l24)
#> Item low neutral
#> 10 I like to express my opinions about books I have read. 41.07516 0
#> 5 I feel happy if I receive a book as a present. 46.93475 0
#> 8 I read only to get information that I need. 50.39874 0
#> 7 I enjoy going to a bookstore or a library. 51.21231 0
#> 3 I like talking about books with other people. 54.99129 0
#> 11 I like to exchange books with my friends. 55.54115 0
#> 2 Reading is one of my favorite hobbies. 56.64470 0
#> 1 I read only if I have to. 58.72868 0
#> 4 I find it hard to finish books. 65.35125 0
#> 9 I cannot sit still and read for more than a few minutes. 76.24524 0
#> 6 For me, reading is a waste of time. 82.88729 0
#> high mean sd
#> 10 58.92484 2.604913 0.9009968
#> 5 53.06525 2.466751 0.9446590
#> 8 49.60126 2.484616 0.9089688
#> 7 48.78769 2.428508 0.9164136
#> 3 45.00871 2.328049 0.9090326
#> 11 44.45885 2.343193 0.9609234
#> 2 43.35530 2.344530 0.9277495
#> 1 41.27132 2.291811 0.9369023
#> 4 34.64875 2.178299 0.8991628
#> 9 23.75476 1.974736 0.8793028
#> 6 17.11271 1.810093 0.8611554plot(l24)
#> Warning: The `size` argument of `element_rect()` is deprecated as of ggplot2 3.4.0.
#> ℹ Please use the `linewidth` argument instead.
#> ℹ The deprecated feature was likely used in the likert package.
#> Please report the issue at <https://github.com/jbryer/likert/issues>.
#> This warning is displayed once per session.
#> Call `lifecycle::last_lifecycle_warnings()` to see where this warning was
#> generated.
l24g <- likert(items24[,1:6], grouping=pisaitems$CNT)
print(l24g)
#> Group Item
#> 1 Canada I read only if I have to.
#> 2 Canada Reading is one of my favorite hobbies.
#> 3 Canada I like talking about books with other people.
#> 4 Canada I find it hard to finish books.
#> 5 Canada I feel happy if I receive a book as a present.
#> 6 Canada For me, reading is a waste of time.
#> 7 Mexico I read only if I have to.
#> 8 Mexico Reading is one of my favorite hobbies.
#> 9 Mexico I like talking about books with other people.
#> 10 Mexico I find it hard to finish books.
#> 11 Mexico I feel happy if I receive a book as a present.
#> 12 Mexico For me, reading is a waste of time.
#> 13 United States I read only if I have to.
#> 14 United States Reading is one of my favorite hobbies.
#> 15 United States I like talking about books with other people.
#> 16 United States I find it hard to finish books.
#> 17 United States I feel happy if I receive a book as a present.
#> 18 United States For me, reading is a waste of time.
#> Strongly disagree Disagree Agree Strongly agree
#> 1 25.69810 35.12856 24.883834 14.289507
#> 2 26.77758 35.18871 24.636078 13.397637
#> 3 25.22917 31.68150 33.470617 9.618706
#> 4 31.33106 40.44088 19.698110 8.529946
#> 5 23.48092 26.65869 37.827417 12.032974
#> 6 40.10368 35.61966 13.961629 10.315034
#> 7 21.87500 36.76845 33.455259 7.901293
#> 8 15.26451 36.42523 37.790775 10.519491
#> 9 18.44410 34.78607 37.891496 8.878331
#> 10 21.09309 39.92260 31.072413 7.911896
#> 11 15.49158 27.46583 42.867359 14.175230
#> 12 44.76067 43.63501 8.519394 3.084928
#> 13 17.16996 33.00426 33.972125 15.853659
#> 14 29.08282 40.51858 21.033282 9.365325
#> 15 24.31646 35.13671 32.790382 7.756448
#> 16 25.32455 43.61558 22.960667 8.099206
#> 17 28.66007 33.37212 30.715532 7.252278
#> 18 33.17811 40.82266 15.851766 10.147458
summary(l24g)
#> Group Item low
#> 1 Canada I read only if I have to. 60.82666
#> 2 Canada Reading is one of my favorite hobbies. 61.96628
#> 3 Canada I like talking about books with other people. 56.91068
#> 4 Canada I find it hard to finish books. 71.77194
#> 5 Canada I feel happy if I receive a book as a present. 50.13961
#> 6 Canada For me, reading is a waste of time. 75.72334
#> 7 Mexico I read only if I have to. 58.64345
#> 8 Mexico Reading is one of my favorite hobbies. 51.68973
#> 9 Mexico I like talking about books with other people. 53.23017
#> 10 Mexico I find it hard to finish books. 61.01569
#> 11 Mexico I feel happy if I receive a book as a present. 42.95741
#> 12 Mexico For me, reading is a waste of time. 88.39568
#> 13 United States I read only if I have to. 50.17422
#> 14 United States Reading is one of my favorite hobbies. 69.60139
#> 15 United States I like talking about books with other people. 59.45317
#> 16 United States I find it hard to finish books. 68.94013
#> 17 United States I feel happy if I receive a book as a present. 62.03219
#> 18 United States For me, reading is a waste of time. 74.00078
#> neutral high mean sd
#> 1 0 39.17334 2.277647 1.0001779
#> 2 0 38.03372 2.246538 0.9946381
#> 3 0 43.08932 2.274789 0.9467191
#> 4 0 28.22806 2.054269 0.9211851
#> 5 0 49.86039 2.384124 0.9730841
#> 6 0 24.27666 1.944880 0.9748120
#> 7 0 41.35655 2.273828 0.8912875
#> 8 0 48.31027 2.435652 0.8726738
#> 9 0 46.76983 2.372041 0.8832303
#> 10 0 38.98431 2.258031 0.8783913
#> 11 0 57.04259 2.557262 0.9165585
#> 12 0 11.60432 1.699286 0.7521860
#> 13 0 49.82578 2.485095 0.9541627
#> 14 0 30.39861 2.106811 0.9298025
#> 15 0 40.54683 2.239868 0.9077166
#> 16 0 31.05987 2.138345 0.8875999
#> 17 0 37.96781 2.165600 0.9255214
#> 18 0 25.99922 2.029686 0.9463031