Development Survey (LDS) (Rescorla, 1989) uses parents’ reports
of vocabulary and word combinations to identify language delays
in children at ages 18-35 months. It can be completed independently
by a parent in about 10 minutes and requires only fifth grade
Over the past
20 years, the LDS has been used with thousands of children. Parents
ranging widely in socioeconomic status and education have provided
reliable and valid reports of their children’s early language
development using the LDS (Klee, Carson, Gavin, Hall, Kent, &
Reece, 1998; Rescorla, 1989; Rescorla & Alley, 2001; Rescorla,
Hadicke-Wiley, & Escarce, 1993). The LDS can be completed
in waiting rooms, daycare centers, preschools, and homes. A Latino
Spanish language version is included with the Latino Spanish Child
Behavior Checklist/1½-5 (CBCL/1½-5/LDS). Several studies
report findings for Latino children (Patterson, 1998; Stelzer,
1995), and there are translations in several other languages.
The LDS includes
310 words arranged into 14 semantic categories (e.g., food, animals,
people, vehicles). Parents are asked to circle each word the child
uses spontaneously. They are also asked to indicate whether their
child uses word combinations. If so, they are requested to write
down five of their child’s longest and best phrases or sentences.
The LDS words were chosen on the basis of diary studies of early
vocabulary development. The LDS went through many revisions, with
lengths ranging from 240 to 353 words. The current 310-word version,
which has been used for more than a decade, contains many high
frequency words (e.g., daddy), as well as less common
words (e.g., yellow).
Most LDS research
has been done with children around 24 months of age. In these
studies, mean LDS vocabulary scores at 24 months have been between
175 and 195 words, with standard deviations in the range of 70
to 80 (Klee et al., 1998; Rescorla & Alley, 2001). Mean vocabulary
scores have generally been higher for girls than boys. LDS vocabulary
has been shown to be significantly related to socioeconomic status
(SES) in samples where the SES range is wide (Rescorla, 1989).
LDS studies have indicated high test-retest reliability (.97-.99)
(Patterson, 1998; Rescorla, 1989; Rescorla & Alley, 2001)
and high Cronbach’s alpha internal consistency (.99) (Rescorla,
1989). Across many samples, correlations between LDS vocabulary
score and number of objects and pictures named on various instruments
have ranged from .66 to .87, indicating a high degree of congruence
between parent-reported vocabulary scores on the LDS and tested
vocabularies (Klee et al., 1998; Rescorla, 1989; Rescorla &
Alley, 2001; Rescorla et al., 1993).
have used the LDS to assess the prevalence of expressive language
delays at 24 months (Klee et al.,1998; Rescorla, 1989; Rescorla
& Alley, 2001; Rescorla et al., 1993). These studies have
typically used a cut-off of fewer than 50 words or no multi-word
combinations at 24 months. Delay rates using this cut-off have
ranged from 10-20%, with boys having higher rates of delay than
girls. Concurrent validity of the LDS using hit rate
analysis has also been reported, with the child’s performance
on a directly administered language test used as the gold
standard for true delay. Sensitivity (percent
of truly delayed identified as delayed by the LDS)
was 87% in Rescorla (1989), 90% and 100% in Rescorla et al. (1993),
91% in Klee et al. (1998), and 80% in Rescorla & Alley (2001).
Specificity (percent of truly not delayed identified
as such on the LDS) was 85% in Rescorla (1989), 90% and 95% in
Rescorla et al. (1993), 87% in Klee et al. (1998), and 94% in
Rescorla & Alley (2001).
Alley (2001) found that children identified as delayed by the
LDS were more than 30 times as likely to be identified as delayed
in subsequent testing with the Reynell Expressive Language Scale
than were children who were not identified as delayed on the LDS
(odds ratio of 34).
In the 1999-2000
National Survey of Children, Youths, and Adults (Achenbach &
Rescorla, 2001), normative data for the LDS were obtained for
278 children ranging in age from 18 to 35 months. The survey sample
was very diverse in SES level (19% lower, 48% middle, 33% upper-middle
and upper) and ethnicity (57% white, 22% African-American, 13%
Latino, 8% other). Girls had significantly higher vocabulary scores
than boys in all age groups, but the gender difference was not
significant for average length of phrases. SES had small but significant
correlations with LDS vocabulary score and average length of phrases
(.14, p < .05, and .18, p < .01, respectively).
norms for vocabulary are provided for ages 18-23, 24-29, and 30-35
months. Scores at or below the 15th percentile suggest
delayed vocabulary development. For average length of phrases,
norms are provided only for ages 24-29 and 30-35 months, because
many children do not combine words into phrases prior to 24 months.
Scores at or below the 20th percentile suggest delayed
References: Achenbach, T. M., & Rescorla, L.
A. (2000) Manual for the ASEBA Preschool Forms & Profiles.
Burlington, VT: University of Vermont Department of Psychiatry.
Klee, T., Carson, D. K., Gavin, W. J., Hall, L., Kent, A., &
Reece, S. (1998). Concurrent and predictive validity of an early
language screening program. Journal of Speech, Language, and
Hearing Research, 41, 627-641.
Patterson, J.L. (1998). Expressive vocabulary development and
word combinations of Spanish-English bilingual toddlers. Journal
of Speech and Language Pathology, 7, 46-56.
Rescorla, L. (1989). The Language Development Survey: A screening
tool for delayed language in toddlers. Journal of Speech and
Hearing Disorders,54, 587-599.
Rescorla, L., & Alley, A. (2001). Validation of the Language
Development Survey (LDS): A parent report tool for identifying
language delay in toddlers. Journal of Speech, Language, and
Hearing Research, 44, 434-445.
Rescorla, L., Hadicke-Wiley, M., & Escarce, E. (1993). Epidemiological
investigation of expressive language delay at age two. First
Language, 13, 5-22.
Stelzer, S. C. (1995). Adaptacion, normalizacion, y estudios
de validez del sondeo del desarrollo de lenguaje (SDL)
para la deteccion de retraso de lenguaje expresivo en niños
Mexicanos de 15 a 31 meses de edad. Mexico City: Universidad
de las Americas.