Samsung SONOACE R7 Bedienungsanleitung PDF herunterladen (Seite 318)

5-144

Operation Manual

Tips!

Standard Deviation & Percentile

Among OB information, the Growth Table and the typical fetal distribution for the same number of

weeks are used to determine the following information:

X

The normal distribution curve.

X

The measurements for an actual fetus or a position in EFW distribution.

X

Whether a distribution point is within the normal range.

The reference number of weeks for the Growth Table can be set to LMP, Estab. DD or Average US GA

under [Pctl.Criteria]. The typical setting is LMP.

When LMP is not known or uncertain, or when the diﬀerence between LMP and Average US GA

is substantial, care must be taken, as selecting diﬀerent [Pctl.Criteria] can result in a signiﬁcant

diﬀerence.

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 5.28 The distribution of the Growth Table for the selected number of weeks

(m: Average,

: 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.

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Samsung SONOACE R7 Bedienungsanleitung Seite 318