Here is some more percentile weirdness from Stanford Achievement:
My son appeared to score in the 98th percentile in total reading (89/90 raw score), 99th percentile in total math (49/50 raw score), aced the rest of the test (100% right), but his total battery percentile is only 93rd....all I can tell from this is he is somewhere between 93rd and 99th (I think)...I have had a few stats classes in college/post grad...this doesn't make sense....the math, reading and total percentiles shown below cannot be correct simultaneously.
In detail, here are my son's 1st Grade Stanford 10 Achievement Test Scores:
Total Reading: 89/90, Nat'l PR-S = 98-9, Nat'l NCE = 93.3
Total Math: 49/50, Nat'l PR-S = 99-9, Nat'l NCE = 99.0
Language: 30/30, Nat'l PR-S = 98-9, Nat'l NCE = 93.2
Spelling: 30/30, Nat'l PR-S = 89-8, Nat'l NCE = 75.8
Environment: 30/30, Nat'l PR-S = 99-9, Nat'l NCE = 99.0
Total Battery: 228/230, Nat'l PR-S = 93-8, Nat'l NCE = 80.9
PR-S = percentile rank-stanine
NCE = normal curve equivalent
Let's equate a correct answer as a step forward, and 100 students take such steps...at the end of the reading section, my son has taken 89 steps forward, and per Stanford (98th percentile in reading), ~2 other students are at or above 89 steps, the rest have less than 89 steps forward....after math, he has now taken 138 steps forward (89+49), and per Stanford (99th percentile in math), only one other student could be at that number of total steps (138), as only one other student took 49 steps forward in math....now even if all 100 students take 30 steps forward for the remaining 3 tests (90 steps total), only one other student would appear to be at 228/230 steps at the end of the total battery per the component percentiles, yet Stanford is saying 7 other students are (93rd percentile)....something doesn't appear right with the data they are presenting.
