Lexile, MAP and SRI Glossary

Lexile (L), MAP (M) , SRI (S) Glossary

bullet Accountability (L) (S) (M)
bullet Alignment (L)
bullet Authentic-Text Passages (S)
bullet Average Growth Index (M)
bullet Beginning Reader (BR) (S)
bullet Cloze (S)
bullet Computer-Adaptive (S)
bullet Content Standards (L)
bullet Criterion-referenced (L) (S)
bullet DesCartes: A Continuum of Learning (M)
bullet Differentiated Instruction (L) (S)
bullet Embedded Completion (S)
bullet Equal-interval (M)
bullet Forecasted Comprehension Rate(L)
bullet Grade Equivalent(L) (S)
bullet Growth Index (M)
bullet Leaders’ Edge: Growth Analysis Tool (M)
bullet Learning Continuum (M)
bullet Lexile(L) (S)
bullet Lexile Framework(L) (S) (M)
bullet Lexile Map(L) (S) (M)
bullet Lexile Range(L) (S)
bullet Lexile Reader Measure(L)
bullet Lexile Scale(L)
bullet Lexile Text Measure (L)

Mean (M)


Median (M)

bullet Norm-referenced(L)
bullet Normal Curve Equivalent (NCE) (L)

Normative Data (M)

bullet Norms Study (M)
bullet One Year's Growth” (S)
bullet Percent Meeting Growth Target (M)

Percent of Target Met (M)

bullet Percentile Rank(L) (M)
bullet Performance Standards(L)
bullet Reading Ability(L)
bullet Readability(L)
bullet RIT (M)

RIT Point Growth Norms (M)

bullet RIT Range (M)
bullet Semantic Difficulty(L)
bullet SRI (S)
bullet Standard Deviation (M)

Standard Error of Measurement (SEM)(L) (M)

bullet Stanine(L)

Syntactic Complexity(L)

bullet Targeted Reading Experience (L)

Triangulation (M)

bullet Types of Tests (M)
bullet Uncertainty(L)
bullet Zone of Proximal Development (M)


The systematic use of assessment data and other information to assure those inside and outside of the educational system that schools are moving in desired directions. Commonly included elements are goals, indicators of progress toward meeting those goals, analysis of data, reporting procedures and consequences or sanctions. Accountability often includes the use of assessment results and other data to determine program effectiveness and to make decisions about resources, rewards and consequences.



Refers to the similarity or match between and among content standards, performance standards, curriculum, instruction, and assessment in terms of knowledge and skill expectations. The inferences made on the basis of assessment results are valid only to the extent that the system components are aligned.


Authentic Text Passages:

All SRI test questions are based on authentic text passages, both fiction and nonfiction, that increase test validity as well as student interest and motivation. All items in the item bank are based exclusively on passages from authentic children’s books, both fiction and nonfiction, as well as excerpts from young adult and classic literature, newspapers, magazines, and periodicals


Average Growth Index

Average growth index is a statistic that appears on some NWEA Reports. It is the total growth index of the group divided by the total number of students in the group.


Beginning Reader (BR)

A text or student with a Lexile measure of 99 or below. BR designation is an indication that the student cannot yet comprehend continuous text.



Cloze is a deletion procedure used to measure syntactic and semantic understanding. In the basic cloze test, after the eighth or tenth word of a selection, every seventh or tenth word (the value varies depending on the approach) is deleted, including function words such as articles, conjunctions, etc.. SRI does not use a strict cloze procedure to create questions. No words are deleted from the passages that students are presented. Only the embedded completion items, described above, omit a word or phrase, and the rules for this missing word differ from those used to create traditional cloze reading test passages. The blanks or missing phrases are designed to assess specific aspects of a student’s comprehension of the reading selection and thereby provide a much more complete and in-depth measure of reading comprehension than conventional cloze test items.


Content Standards
Statements of knowledge and skills that schools are expected to teach and students are expected to learn. They indicate what students should know and be able to do as a function of schooling.



The test’s level of difficulty automatically adjusts in response to students’ answers, resulting in fast, accurate assessment, with no “test burnout” for students.



A test where the results are interpreted in relation to the specific knowledge or skills possessed by a student. Such tests usually cover relatively small units and are related to instruction. Performance is measured in reference to the mastery of particular skills. Scores from these tests have meaning in terms of what the student knows or can do, rather than in relation to the scores made by some external reference (or norm) group.



DesCartes: A Continuum of Learning

DesCartes translates test scores into skills and concepts students may be ready to learn. It orders specific reading, language usage, mathematics, and science skills and concepts by achievement level. For reading, language usage, and mathematics, the skills and concepts align to the goal structures and content of a state’s standards. For science, the skills and concepts align to national standards for the two domains of science: concepts and processes and general science. For easy reference, the skills and concepts are grouped along the continuum according to the NWEA measurement scale.


Differentiated Instruction
The attempt "on the part of classroom teachers to meet students where they are in the learning process and move them along as quickly and as far as possible in the context of a mixed-ability classroom" (Tomlinson, 1999). Differentiated instruction promotes high-level and powerful curriculum for all students, but varies the level of teacher support, task complexity, pacing, and avenues to learning based on student readiness, interest and learning profile.


Embedded Completion

An item format, which is similar to the fill-in-the-blank or cloze format and directly assesses the reader’s ability to draw inferences and establish logical connections between the ideas in the passage.



The RIT scale is theoretically infinite, but most student scores fall between the values of 100 and 300. Like meters or pounds, the scale is equal-interval, meaning that the distance between 170 and 182 is the same as the distance between 240 and 252. This allows educators to apply simple mathematical equations to the scores to determine information such as the mean and median scores in a class or grade.


Forecasted Comprehension Rate

The Lexile Framework for Reading is based on a conjoint measurement model such that a reader and a text are placed on the same scale, the Lexile scale. When the reader measure and the text calibration are the same (difference of 0L) then the forecasted comprehension rate is 75 percent. When the difference between the reader measure and the text calibration is -250L (the text is more difficult than the reader is able), then forecasted comprehension rate falls to 50 percent. Conversely, when the difference between the reader measure and the text calibration is +250L (the reader is more able than the text is difficult), then forecasted comprehension rate improves to 90 percent.


Grade Equivalent

A score that represents the typical (mean or median) performance of students tested in a given month of the school year. It is a decimal number that shows performance in terms of grade level (to the left of the decimal) and months (to the right of the decimal).


Growth Index

The growth index is a statistic that appears on some NWEA reports. The growth index indicates the RIT value by which the student exceed the target RIT (plus values), fell short of the target RIT (minus values), or exactly met the target RIT (0). The target RIT is determined by the NWEA RIT Point Growth Norms.


Leaders’ Edge: Growth Analysis Tool

NWEA Leaders’ Edge is a powerful, computer-based analysis tool. With it, educators can analyze data from the district level down to the individual student. Grouping and disaggregation features enable creation of reports and charts to meet an individual district’s or school’s need.


Learning Continuum

The NWEA Learning Continuum is a document listing skills and concepts that appear in the NWEA item banks. In the fall of 2004, the Learning Continuum was dramatically expanded and improved. See also DesCartes: A Continuum of Learning.


A unit of measurement used when determining the difficulty of text and the reading level of readers. A Lexile is equivalent to 1/1000th of the difference between the comprehensibility of basal primers (the midpoint of first grade text) and the comprehensibility of an electronic encyclopedia (the midpoint of workplace text).



Lexile Framework

The Lexile Framework for Reading is a system that can help determine the reading level of any written material-from a book to a test item. The Lexile Framework can also be used to assess a readers' reading comprehension level. After test results are converted into Lexile measures, readers can be matched to reading materials on their own level and comprehension rates of readers can be forecasted to determine how well the reader will comprehend thousands of texts that have been measured in the Lexile metric.


Lexile Map

The Lexile map provides a context for understanding reading comprehension test results-it is a window to the Lexile Book Database. The map contains representative literary titles and everyday texts, foundation titles, tests and textbooks and educational levels correlated with the Lexile scale. The educational levels on the Lexile map provide a classroom context for the Lexile measures. Within any one classroom there will be a range of readers and a range of reading materials. For example, in a fifth-grade classroom students will be reading from the third-grade level to the eighth-grade level. Conversely, in a fifth-grade classroom there will be reading materials at the third-grade level to the eighth-grade level.


Lexile Range

The suggested range of Lexiles at which the reader should be reading. The Lexile range for a reader is from 50L above her or his Lexile measure to 100L below. For independent reading, insreuctional reading, and fluent reading. The ranges for each of these are usually:

  • Independent: 250 Lexiles below the student's Lexile measure to 50 Lexiles above the student's Lexile measure.
  • Instructional: 250 Lexiles below the student's Lexile measure to 100 Lexiles above the student's Lexile measure.


Lexile Reader Measure

A Lexile reader measure is the specific number that describes a student's reading comprehension skills. This can be accomplished through formal methods such as a linking study where the reporting scale of a norm-referenced or criterion-referenced assessment is linked with the Lexile scale, or through informal methods such as listening to a student read a book with a known Lexile measure.


Lexile Scale

The Lexile scale ranges from 200 to 1700 Lexiles (200L to 1700L), although actual Lexile measures can range from below zero to above 2000 Lexiles (below 0L to above 2000L).


Lexile Text Measure

A Lexile text measure is the specific number assigned to any text indicating the reading demand of the text in terms of the semantic difficulty (vocabulary) and syntactic complexity (sentence length). A computer program called the Lexile Analyzer computes it. The Lexile Analyzer carefully examines the whole text to measure such characteristics as sentence length and word frequency-characteristics that are highly related to overall reading comprehension. The Lexile Analyzer then reports a Lexile measure for the text.



The mean is the arithmetic average of a group of scores. The mean is sensitive to extreme scores when population samples are small.



The median is the middle score in a list of scores; it is the point at which half the scores are above and half the scores are below.


Normal Curve Equivalent (NCE)

A normal curve equivalent (NCE) is a normalized student score with a mean of 50 and a standard deviation of 21.06. NCEs range from 1 to 99. NCEs allow comparison between different tests for the same student or group of students and between different students on the same test. NCEs have many of the same characteristics as percentile ranks, but have the additional advantage of being based on an interval scale. That is, the difference between two consecutive scores on the scale has the same meaning throughout the scale. NCEs are often required by many categorical funding agencies (for example, Title I).



A test where the results are interpreted in relation to the performance of a comparison group. Norm-referenced interpretations tell how the scores of each student or group of students compares to the scores of the original (norm) group that took the test. The scores of the students do not necessarily produce the same distribution of scores as the scores of the norm group.


Normative Data

A preliminary reference point for educators to compare class or grade-level performance of students in the same grade from a wide variety of schools throughout the nation.


Norms Study

The NWEA RIT Scale Norms describe the performance and growth of students from school systems that volunteered to participate in the most recent study. The study provides a reasonable way to compare the performance of a single student, school, or school district to a larger, meaningful reference group.


“One Year's Growth”

There are several ways of measuring “one year’s worth of growth.” If the student is in seventh grade, for example, one way to interpret one year’s growth is by finding the difference between the Lexile score at the 50th percentile in seventh grade and the Lexile score at the 50th percentile in eighth grade. It is important to note, however, that reading development is not linear; that younger students are expected to show more growth than older students. With that in mind, if the seventh grader above is actually reading at a second-grade level, one could also review the growth expectations from the 50th percentile in second grade to the 50th percentile in third grade, a larger difference than would be calculated in the first example


Percent Meeting Growth Target

This is the total student growth divided by the total of target RITs expressed as a percentage. It shows the proportion of the overall RIT growth targets achieved by the students. Performance of 100 percent is considered average, meaning the student growth equaled the targets. This is used in conjunction with the “Percentage of Students who Met or Exceed their Target RIT.”


Percent of Target Met

The Percent of Target Met is a statistic that appears on some NWEA reports. It is the total student growth divided by the total of the student growth targets.


Percentile Rank

The percentile rank of a score indicates the percentage of scores less than or equal to that score. Percentile ranks range from 1 to 99. For example, if a student scores at the 65th percentile rank, it means that he or she preformed as well as or better on the assessment than 65 percent of the norm group. Real differences in performance are greater at the ends of the percentile range than in the middle. Percentile ranks of scores can be compared across two or more distributions; percentile ranks cannot be used to determine differences in relative rank due to the fact that the interval between adjacent percentile ranks do not necessarily represent equal raw score intervals. Caution: It should be noted that the percentile rank does not refer to the percentage of items answered correctly. For MAP - This number indicates the percentage of students in the NWEA norm group for this grade that this student’s score equaled or exceeded.


Performance Standards

What students must do to demonstrate various levels of proficiency with respect to the specific content. More and more, educators and parents want to know more than just how a student's performance compares with that of other students: of growing interest is "What level of performance does a score represent?" and "How good is good enough?" Performance standards consist of four components: (1) performance levels which provide descriptive labels for student performance, e.g., "advanced," "proficient;" (2) descriptions of what students at each performance level must demonstrate relative to the test; (3) examples of student work that illustrate the range of performance for each performance level; and (4) cut scores which separate one level of performance from another. For any test scale a number of points can be identified that correspond to a specified level of performance. For example, on the National Assessment of Educational Progress (NAEP) three levels of performance are identified: basic, proficient and advanced. Proficient achievement on the NAEP reading assessment is defined as "solid academic performance for each grade assessed. Students reaching this level have demonstrated competency over challenging subject matter, including subject-matter knowledge, application of such knowledge to real-world situations and analytical skills appropriate to the subject matter" (NAGB, 1999).


Reading Ability

The reading comprehension skills of the reader



The difficulty level (reading demand) of the text



Tests developed by NWEA use a scale called RIT to measure student achievement and growth. RIT stands for Rasch unIT, which is a measurement scale developed to simply the interpretation of test scores. The RIT scores relates directly to the curriculum scale in each subject area. It is an equal-interval scale, like feet and inches, so scores can be added together to calculate accurate class or school averages. RIT scores range from about 100 to 300 depending upon the scale and test season. They make it possible to follow a student’s educational growth from year to year.


RIT Point Growth Norms

RIT Point Growth Norms are tables that allow educators to get a more realistic look at growth across various starting RIT scores at each grade level. These norms establish typical student growth relative to other students in the NWEA norming study who started with the same RIT score in the same grade.


RIT Range

The RIT range reflects the rounded range of scores that is one standard error of measure around the student’s RIT score



Semantic Difficulty

The difficulty of the words in a text. Most operationalizations of semantic difficulty are proxies for the probability that an individual will encounter a word in a familiar context and thus be able to infer its meaning. The Lexile Framework currently employs a nearly 600-million-word corpus when examining the semantic component of text. This corpus was assembled from the 44,000-plus texts that were measured by MetaMetrics for publishers from 1998 through May 2003.



A research-based, computer-adaptive reading assessment for Grades K–12 that measures students’ level of reading comprehension and reports it using the Lexile Framework® for Reading.


Standard Deviation

Standard deviation is a statistic expressing the homogeneity/heterogeneity of instructional level of a group of students. The larger the standard deviation, the more academically diverse the group.


Standard Error of Measurement (SEM)

The SEM is an index of test uncertainty. It allows us to estimate the amount of each type of error associated with “true” scores. We can compute standard errors of measurement for raters, occasions and item samples. Statistically, the SEM is the standard deviation of the error scores of a test. For MAP -- The standard error or measurement is an estimate of the precision of the achievement (RIT) score. The smaller the standard error, the more precise the achievement estimate is.



A stanine is a standardized student score with a mean of 5 and a standard deviation of 2. Stanines range from 1 to 9. In general, stanines of 1 to 3 are considered below average, stanines of 4 to 6 are considered average and stanines of 7 to 9 are considered above average. A difference of 2 between the stanines for two measures indicates that the two measures are significantly different. Stanines, like percentiles, indicate a student's relative standing in a norm group.


Syntactic Complexity

The complexity of the sentence structure in a text. Based on previous research, it was decided to use sentence length as a proxy for the syntactic component of reading difficulty in the Lexile Framework. The research of various individuals has provided evidence that sentence length is a good proxy for the demand that structural complexity places upon verbal short-term memory.


Targeted Reading Experience

An interaction between a reader and a text where the reader is challenged by new vocabulary and varying sentence structures, but is not overwhelmed. A 1000L reader reading 1000L text (75 percent comprehension) reports confidence, competence and control over the text. Teachers listening to such a reader report that the reader can sustain the meaning thread of the text and can read with motivation and appropriate emotion and emphasis. In short, such readers appear to comprehend what they are reading. This value, 75 percent, was selected to ensure that texts selected are not so hard that the reader experiences frustration and loses the meaning-thread of the text, but, at the same time, is not so easy that the reader does not experience any challenge. When the measure for a text is 250L above the reader's measure, comprehension drops to 50 percent and the reader experiences frustration and inadequacy. Conversely, when the measure of a text is 250L below a reader's measure, comprehension goes to 90 percent and the reader experiences total control and automaticity.



Triangulation refers to the process of looking at multiple points of data, typically three supporting pieces that agree, to make informed decisions about students and/or academic programs. Three or more scores can be referred to as a “body of evidence.”


Types of Tests

  • Survey Test :A 20-item test that gives an overall RIT score for the subject but does not provide goal performance scores. It takes about 30 minutes to administer and is most commonly used for course placement and intake testing.

  • Goal Survey Test: A 42-64 item test in Mathematics, Reading, Language Usage, and Science that gives an overall RIT score for the subject as well as scores in each of the goal performance areas. It takes about an hour to administer and is typically given in the fall and spring. Many districts also use this test in winter when assessing the effectiveness of specific instructional strategies that have been implemented after fall testing.

  • End-of-Course Test: A single level test that evaluates the content of an entire course of study which may be completed in an academic year or in a semester in one main area of concentration in Mathematics. End-or-Course tests are administered at the end of a course only and are not intended to be used as a pre-test. MAP 6+ Mathematics may be used as a pre-test with End of Course tests as the post-test if a growth measured is desired.

  • MAP for Primary Grades Prerequisite Tests: Diagnostic tests with results reported in both percent and number correct; measure the foundational skills of letter and number understanding.

  • MAP for Primary Grades Skills Checklist Tests: Diagnostic tests with results reported in both percent and number correct; extend student assessment beyond the Prerequisite test and are used to inform instruction and to evaluate the attainment of foundation skills in mathematics and reading.

  • MAP for Primary Grades Survey with Goals Tests: Four adaptive tests in Reading and Mathematics with results reported in RIT scores.



All assessments — national norm-referenced tests, state-level criterion-referenced tests, interest inventories and diagnostic surveys — have some inherent measurement error, or uncertainty. The source of the measurement error may be the test, the reader, or the interaction between the test and the reader. Every test has some inherent measurement error related to the how the test items are developed and calibrated, and the number of questions that are asked. In addition, the reader always provides some level of measurement error, e.g. prior knowledge, health and motivation. It is expected that some students may not score consistently due to other sources of measurement error internal to the student. It is advisable to go back and review the testing experiences of these students to better understand what is happening. As with any test, teacher judgment as to the validity of the testing session and the results should be reviewed. There are days when students are not in the mood to take a test and, therefore, do not take the test


Zone of Proximal Development

Scientific studies of learning have shown that an optimal match can be made between any given learner’s background knowledge and current achievement with the introduction of new ideas and skills to produce maximum growth. This match is called the “zone of proximal development.” vygotsky, L.S. (1978). Mind in society: The development of higher psychological processes. Cambridge, MA: Harvard University Press.


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