descript  R Documentation 
Computes descriptive statistics for dichotomous and polytomous response matrices.
descript(data, n.print = 10, chi.squared = TRUE, B = 1000)
data 
a 
n.print 
numeric indicating the number of pairwise associations with the highest pvalues to be printed. 
chi.squared 
logical; if 
B 
an integer specifying the number of replicates used in the Monte Carlo test (i.e., this is the 
The following descriptive statistics are returned by descript()
:
the proportions for all the possible response categories for each item. In case all items are dichotomous, the logit of the proportion for the positive responses is also included.
the frequencies of all possible total scores. The total score of a response pattern is simply its sum.
For dichotomous items this is the number of positive responses, whereas for polytomous items this is
the sum of the levels represented as numeric values (e.g., the response categories "very concerned",
"slightly concerned", and "not very concerned" in Environment
are represented as 1, 2,
and 3).
Cronbach's alpha, for all items and excluding each time one of the items.
for dichotomous response matrices two versions of the point biserial correlation of each item with the total score are returned. In the first one the item is included in the computation of the total score, and in the second one is excluded.
pairwise associations between items. Before an analysis with latent variable models, it is useful to
inspect the data for evidence of positive correlations. In the case of binary or polytomous data, this
ad hoc check is performed by constructing the 2 by 2 contingency tables for all
possible pairs of items and examine the Chisquared pvalues. In case any expected frequencies
are smaller than 5, simulate.p.value
is turned to TRUE
in chisq.test()
,
using B
resamples.
descript()
returns an object of class descript
with components,
sample 
a numeric vector of length 2, with elements the number of items and the number of sample units. 
perc 
a numeric matrix containing the percentages of negative and positive responses for each item. If

items 
a numeric matrix containing the frequencies for the total scores. 
pw.ass 
a matrix containing the pvalues for the pairwise association between the items. 
n.print 
the value of the 
name 
the name of argument 
missin 
a numeric matrix containing the frequency and percentages of missing values for each item;
returned only if any 
bisCorr 
a numeric vector containing sample estimates of the biserial correlation of dichotomous manifest variables with the total score. 
ExBisCorr 
a numeric vector containing sample estimates of the biserial correlation of dichotomous manifest variables with the total score, where the latter is computed by excluding the specific item. 
data 
a copy of the 
alpha 
a numeric matrix with one column containing the sample estimates of Cronbach's alpha, for all items and excluding each time one item. 
Dimitris Rizopoulos d.rizopoulos@erasmusmc.nl
plot.descript
,
unidimTest
## Descriptives for LSAT data: dsc < descript(LSAT, 3) dsc plot(dsc, type = "b", lty = 1, pch = 1:5) legend("topleft", names(LSAT), pch = 1:5, col = 1:5, lty = 1, bty = "n")
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