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|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 ...