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Standard Deviation/Standard Score Correspondence - how to do standard deviation
|Standard Deviation/Standard/Scaled Score Correspondence |
|Standard Deviation (SD) |Standard Score |Scaled Score |
|2 SD above mean |130 or above |16 or above |
|1 SD above mean |Between 115 and 130 |Between 13 and 16 |
|Within 1 SD of mean |Between 85 and 115 |Between 7 and 13 |
|1 SD below mean |Between 70 and 85 |Between 4 and 7 |
|1.5 SD below mean |77.5 |5.5 |
|2 SD below mean |70 or below |4 or below |
| | | |
From the WJ-III ACH
|Test |Standard Score |Descriptor |Percentile Rank |95% Confidence Interval |Standard Deviation |
|Letter-Word Identification |78 |Low |7 |72 – 83 |- 1.5 SD |
|Reading Fluency |82 |Low Average |12 |79 – 85 |- 1 SD |
|Passage Comprehension |90 |Average |26 |80 – 101 |* |
|Calculation |88 |Low Average |21 |78 – 97 |* |
|Math Fluency |83 |Low Average |13 |78 – 87 |- 1 SD |
|Applied Problems |91 |Average |28 |86 – 96 |* |
|Spelling |77 |Low |7 |70 – 85 |- 1.5 SD |
|Writing Samples |92 |Average |31 |75 – 110 |* |
|Writing Fluency |86 |Low Average |18 |79 – 94 |* |
* Not significant – within 1 standard deviation of the mean
From the TOWRE
| |Score |Percentile |Description |Standard Deviation |
|Sight Word Efficiency |83 |13 |Below Avg. |- 1 SD |
|Phonemic Decoding Efficiency |76 |6 |Poor |- 1.5 SD |
|Total Word Reading Efficiency |75 |5 |Poor |- 1.5 SD |
What is the formula for finding the standard deviation? Standard Deviation, σ = ∑ i = 1 n ( x i − x ¯) 2 n. In the above variance and standard ...
