Clarifying the meaning of Scaled Score and Percentile Rankings.

[knok]

Percentile Rank

 

Percentile rank indicates the student's standing relative to other students in the same grade in the norming group. A student's percentile rank on a norm-referenced test tells us what proportion of students in the norm group scored the same or lower than a target student. For example, a student with a percentile rank of 75, did as well or better than 75 percent of the students in the norm group for the test.

 

Do not confuse percentile rank with percent correct. Percentile rank tells us how the student compares to other students, while percent correct tells us the proportion of correct answers. In other words, percentile rank is definitely not the percent of correct answers.

 

See the report form for more examples of percentile rank scores.

 

Scaled Score

 

Scaled scores tell you how much students' scores deviate from the mean or average score. That is, by looking at a scaled score, you can tell immediately how far above or below the mean a person's score is. The range of the scaled score varies depending on the test maker. Some tests such as the CAT, SAT or GRE, use the same 200-800 scale as this example report form. The ACT uses a scale from 1-36 with a mean of 18. Wechsler IQ scores use a scale of 55-145 with a mean of 100. These scores can be used to compute the average performance for groups of students.

 

See the report form for more details on scaled scores.

 

( Source: http://www.coe.usu.edu/psyc/slehman/nrt/score_type.htm)

 

To make it more clear, please see the example below:

 

Score Yourself:

..GRE Quantitative Ability

 

Once you've taken all four Quantitative Mini-Tests under timed conditions, add up the total number of questions you answered correctly (out of 34). This is your raw score. Then determine your scaled Quantitative score and percentile rank using the table below. [How to Interpret the Table]

 

..raw score | scaled score | percentile rank

 

 

34 ---------- 800 --------- 99

33 ---------- 790 --------- 98

32 ---------- 780 --------- 96

31 ---------- 760 --------- 94

30 ---------- 740 --------- 92

29 ---------- 720 --------- 89

28 ---------- 700 --------- 85

27 ---------- 670 --------- 81

26 ---------- 640 --------- 77

25 ---------- 610 --------- 72

24 ---------- 590 --------- 67

23 ---------- 570 --------- 61

22 ---------- 540 --------- 55

21 ---------- 510 --------- 48

20 ---------- 490 --------- 41

19 ---------- 470 --------- 35

18 ---------- 450 --------- 30

17 ---------- 430 --------- 25

16 ---------- 400 --------- 21

15 ---------- 370 --------- 17

14 ---------- 360 --------- 14

13 ---------- 350 --------- 11

12 ---------- 330 --------- 8

11 ---------- 310 --------- 6

10 ---------- 280 --------- 4

9 ----------- 250 --------- 2

8 ----------- 220 --------- 1

6-7 --------- 210 --------- 1

0-5 --------- 200 --------- 0

 

How to Interpret the Table

 

 

Quantitative scaled scores are based on a 200-800 scale. (There's nothing magic about this number range; it's just GRE testing tradition.)

Percentile ranking (0% to 99%) shows how you performed relative to all others taking the GRE over a recent multi-year period. A percentile ranking of 60, for example, indicates that you scored higher than 60% of all other test takers (and lower than 40% of all other test takers). NOTE: Percentile rankings are not reported to the graduate schools.

 

One additional correct response makes the biggest percentile difference near the middle of the performance "curve" (because it's a typical bell curve).

If you missed 5 or fewer questions out of 34, expect to rank in the top decile (10%) in GRE Quantitative Ability.

If you responded correctly to 21 questions out of 34 questions, expect to rank near the 50th percentile in GRE Quantitative Ability.

 

 

(Source: http://www.west.net/~stewart/gre/score_q.htm)

 

Thanks Trav for the link.

 

I hope that these two links help you understand the meaning of scaled score and percentile ranking.