Samsung ACCUVIX XG Instrukcja Użytkownika Pobierz pdf (Strona 372)

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Operation Manual

The distribution of the number of weeks in the Growth Table for the selected reference is a normal

distribution that is laterally symmetrical around 50% (the average), and it shows the distance

from the average as a deviation. The deviation can be represented by Standard Deviation (SD) or

Percentile.

[Figure 5.37 The distribution of the Growth Table for the selected number of weeks

(m: Average, σ: Standard Deviation)]

When represented by SD, a point near the average indicates a value closer to ±0 SD and a point

away from the average indicates a value closer to the maximum or minimum value. The greater part

of the range falls within ±3 SD, and ±1 SD represents 68.3% of the entire range. Thus it can be seen

that most fetal measurements are tightly clustered around the average value.

The Percentile represents a point in distribution from between 0 and 100 inclusive. Therefore, the

average point is represented as 50 Percentile.

As shown in the figure, the average point corresponds to 0 SD (that is, 50 Percentile). If a point is in

the range between -1 SD and +1 SD, it falls within 68.3% of the entire range. This means that the

point falls within the range between 16 and 84.

Further, if a point is in the range between -2 SD and +2 SD, it falls within 95.5% of the entire range.

Thus, the point falls in the range between 3 and 97.

SD and Percentile are interchangeable. Percentile can be used when a fetal measurement ranking

is desired, and SD can be used when the distance between actual fetal measurements and the

average measurement is sought.

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Samsung ACCUVIX XG Instrukcja Użytkownika Strona 372