Name of Assessment Instrument/Test: Peabody Developmental Motor Scales-2 (PDMS-2)
Author(s): M. Rhonda Folio & Rebecca R. Fewell
Most Recent Publication Date and Edition of Test: Second Edition © 2000
Name of Publisher: PRO-ED, Inc.
Website for Publisher: http://www.proedinc.com
Cost of Total Kit and Reorder of Score Sheets, etc:
Total Cost of Kit: 509.00
Reorder of Score Sheets: 85.00
General Components/Skills Measured:
The Peabody Developmental Motor Scales-2 (PDMS-2) is a test that measures motor abilities typically seen in
the early developmental stages of life. The test can be broken into two categories gross and fine motor and into
six subtests categories including; 8 reflex tests, 30 stationary balance tests, 89 locomotor tests, 24 object
manipulation tests, 26 grasping tests and 72 visual motor integration tests, for a total of 249 tests.
Population(s) Designed for:
The PDMS-2 is designed for individuals from birth through 6 years old with and without disabilities.
Norm- and/or Criterion-Referenced:
The PDMS-2 is criterion and norm referenced test. It is criterion referenced in that each test is designed to
evaluate the performance of the skill. Each test item has specific criteria that is measure to be either proficient,
showing signs of mastery or is not performed. These scores were then normed on over 2,000 children from 46
states and different parts of Canada. There is however no set of norms for individuals with disability.
Technical (or Examiner’s) Manual(s):
The PDMS-2 examiner’s manual is both compact and readily accessible. The first chapter gives a brief overview
of the test breaking it down into the various subtests, and description of all of the test components. Additionally,
this chapter provides the rationale behind the PDMS-2 and lists all equipment required for completion of the test
including those materials that are not provided in the kit. Chapter two explains in detail all of the information
that should be considered before administering the test. This includes considerations for the examiner’s
competence, the amount of time required to administer the test, the best environment to administer the test, and
how to account for situational and subject error. Chapter three explicitly covers the scoring procedures, which
can at first seem very complex to the novice test administrator. It also provides general directions for
administering the test. Chapter four explains how the test administrator should interpret the results of the
PDMS-2. This includes all of the ways the test administrator should convert the tests and what these various
conversions represent. Additionally, this chapter clearly defines the gross, fine and total motor quotients.
Chapter five explains the ways that the test norms were created. This includes how the sample was collected and
the demographic characteristics of the sample. Chapter six explains and provides the results for the test
reliability. It explains in great detail how content and time sampling were evaluated as well as how interscorer
differences were evaluated. Finally, chapter seven covers test validity. Content, criterion, and construct validity
were all evaluated and the processes of this evaluation were explained in great detail. Lastly, the appendixes that
follow serve to help the test administrator convert the various scores so the results can be interpreted.
Standardization (Normative) Procedures:
The PDMS-2 was normed in various sites representing the four major geographic regions of the U.S. These sites
were selected from individuals who had previously purchased the PDMS and individuals who responded to a
mailer asking occupational and physical therapists to test between 20 and 30 individuals. The researchers
received results for 2,003 children from Winter 1997 through Spring of 1998. These results were evaluated in
reference to geographic region, gender, race, rural or urban residence, ethnicity, family income, parent education
and disability (Folio & Fewell, 40). There was no overt effort made to include individuals with a disability,
however those individuals made up ten percent of the normed population. The disabilities included speechlanguage disorder, mental retardation, physical disability and other non-specific disabilities.
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Reliability (Describe procedures the authors used to determine reliability):
The reliability procedures of the PDMS-2 were evaluated separately for gross and fine motor scales and the total
score on content sampling, time sampling and interscorer differences. Content sampling was evaluated using
Cronbach’s coefficient alpha with scores ranging from .89 to .97, which are exceptionally high. Additionally,
the researchers found standard errors of measure (SEMs) for each of the subtests by six different age groups.
These SEMs bands provide a confidence interval ranging from 68% to 99% that individual’s true score lies
within the specified range. The SEMs are relatively low and support a high degree of reliability. Time sampling
is the consistency of an individual’s performance over time and was evaluated using the test-retest method.
Individuals were evaluated within one week and using the coefficient values found support a high reliability in
scores over time. Overall the PDMS-2 was found to be highly reliable.
Validity (Describe procedures the authors used to determine validity):
The validity of PDMS-2 was evaluated for content, construct and criterion validity. Content validity was
evaluated in three different ways. First, the authors clearly defined their rationale for selecting each of the test
items. Second, they ran conventional item analysis procedures and Item Response Theory analyses to choose
test items during test construction. Third, and finally, the lack of bias in a test item is shown by the results of
differential item functioning analysis. Ultimately the content validity demonstrated the results of the PDMS-2
were similar to well documented tests of motor development. Construct validity consisted of an analysis of the
test items to show that the test does in fact measure a specific trait. This was evaluated by using a confirmatory
factor analyses, which confirms the structure of the test, specifically that test items are within correct subtest
category. These analyses showed support for construct validity. Finally, criterion validity which shows that a
test is able to predict an individuals performance in specified activities was evaluated by comparing an
individual’s score on the PDMS-2 with that of the PDMS and the Mullen Scales of Early Learning: AGS
Edition. The correlation coefficients for these two tests were very high and support the criterion validity of the
PDMS-2.
Objectivity or Inter Tester Reliability:
The objectivity of the PDMS-2 was evaluated by having two different trained individuals score tests
independently of each other. The two testers scored two different groups of children one ages 3 to 11 months
and the other ages 15 to 36 months. These test scores were then compared and their coefficients were found to
be high enough, .8 to .96, to support claims of objectivity.
Scoring procedures:
The PDMS-2 has a complex scoring system which requires the test administrator to understand certain unique
scoring terms for this specific test. First the test administrator will score each item on the test by giving a 0, 1 or
2. A student receives a 0 if they cannot complete the task, a 1 if they partially complete it or are showing
promise, and a 2 if they correctly complete the task. Because there are over 200 test items the test administrator
begins a test at the entry level as determined by the child’s age. If the child does not score a 2 at their age level
skills the test administrator tests backwards to find the level they are proficient at. The test administrator then
scores the test and establishes that child’s basal and ceiling level. The basal level is established when a child
scores a 2 three times in succession. This shows that a child is proficient in these skills and scoring begins from
here. It is assumed that all items scored bellow this level the child is equally proficient in because they would
need to have master them in order to be successful on these items. The child continues to test on each item until
they score a 0 three times in a row. This is the child’s ceiling level when this has been established testing stops.
The raw score is comprised of the total score between the basal and ceiling level and every item that came
before the basal level is scored as a 2. The test administrator then converts the raw score into the standard score,
age equivalent and percentile by using the appropriate appendixes. Next the test administrator sums all of the
standard scores of each subtest within either gross or fine motor category. The test administrator takes the sum
of the standard score for the four gross motor subtests and converts that to the Gross Motor Quotient (GMQ)
using the appropriate appendix. The same is done for the two fine motor subtests to find the Fine Motor
Quotient (FMQ). Finally, the test administrator sums all of the subtests standard scores and converts this number
to the Total Motor Quotient (TMQ) using the appropriate appendix. The GMQ and FMQ are the best estimate of
movement abilities for those categories as the TMQ is the best estimate of an individuals overall motor abilities.
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Accompanying Curriculum, Teaching and/or Training Manuals/Materials:
The Motor Activities Program is an accompanying manual that explains in great detail various units individuals
can uses to address motor delays in the any of the 6 specific subtests categories. This manual also discusses the
uses of the PDMS-2 for Individualized Family Service Plans and Individualized Education Plans. Additionally,
the manual discusses how to use the PDMS-2 for setting goals and objectives within these plans. The authors
believe that by using this manual individuals will be able to improve the motor abilities of the child by helping
new skills to emerge by building on the skills the child already possess. The child will learn these skills through
interactions with others. The learning process is emphasized through practice, frequency and making
modifications to facilitate learning. Additionally, the individuals teaching the child must develop safe
environments and learn what motivates the child to learn using objects and people to facilitate the master of the
various skills. The manual is meant to be of benefit to teachers, parents, physical and occupational therapists,
and other caregivers to help facilitate the motor development of the child.
Special or very unique considerations:
The PDMS-2 is a very comprehensive test and as such cannot include all of the materials required to administer
the test. However, the number of items required outside of the test is very large and includes such items as stairs
with a 7 inch rise, that may not be readily available, and others like crayons, pencils and markers that are readily
available. Additionally, the test administrator would be very wise to be extremely familiar with the typical
developmental behaviors that the test is looking for that may not be common to them as a physical therapists or
adapted physical education teacher.
Summary narrative of strengths/advantages of instrument/test/curriculum program:
One of the strengths of the PDMS-2 is the way it is scored and those scores are recorded. The basal and ceiling
levels provide a wealth of information that the test administrator can readily use to monitor progress and
compare a child to their peers. Also the GMQ and TMQ provide information about the child’s overall motor
abilities at a glance. Another strength of this test is that the motor abilities tested closely relate to common areas
in most physical education curriculums like throwing and catching. Because of this the test administrator can
also readily identify any areas that are lacking in development and readily work to correct them. To that end the
Motor Activities Program is an extremely useful tool for any test administrator working to make progress in a
particular motor ability area and can be seen as a great asset to the overall test. Additionally, the group used to
norm the data had a population of ten percent of individuals with disabilities. While this is not as high as would
be seen in the general population it is important to note the inclusion of these individuals into the norm is a
significant detail. One of the final strengths of the test is that it is one of the few tests the places such a great
emphasis on young children who are in the early developmental stages and works to be a tool for early
intervention purposes.
Summary narrative of weaknesses or concerns:
Unfortunately the PDMS-2 provides no normative data specific to individuals with disabilities, even though it
did include individuals with disabilities in the normative population. Also, the fact that the test requires so many
outside items, including very large ones like a set of stairs, is a very large negative. In fact the test administrator
is required to provide more than half of the testing materials. Another concern is the fact that the PDMS-2 tests
certain skills that are not age appropriate such as the overhand throw being assessed for a 3 year old. Finally the
test claims to be designed for individuals age birth to 6 years old but the time required to administer the test is
over 45 minutes. The time demands for the skills being tested are too great for the attention limitations of the
child being tested.
Uses in adapted physical education for individuals with disabilities:
Because the PDMS-2 is both a criterion and norm referenced test is can be used to make identification,
placement and instructional decisions. The norms can easily be used to establish whether or not an individual is
qualified for APE services. The specific criterion needed for each of the subtests make it so an APE teacher can
clearly identify objectives to determine if specific individuals would best be served in an APE setting. Finally,
the test and the Motor Activities Program lends itself to identify areas that need more attention in the
instructional setting and the best ways to work to correct them.
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Practical suggestions regarding administration of this instrument:
Because of the lengthy scoring booklet the test administrator would be wise to have a paraprofessional or aid
record the scores as the test is being administered. Additionally, the skills being evaluated are generally unique
to this test so the test administrator should take the extra effort to learn the specific criteria for each of the tests,
but this could take a great deal of time because of the sheer number of tests. Finally, the test administrator would
be wise to film the child when they are tested. Because of the child’s young age they may lack consistency in
their performance of skill and the ability to replay the specified task may greatly aid the test administrator in
their ability to score the test.
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