MoM value
A MoM value is a unit that relates a measured value to an average value. The MoM value describes how much higher or lower a measured value is in relation to an ideal value.
Origin of the term
The abbreviation “MoM” is derived from the English term “multiple of the median”. Translated, this means: “multiple of the median ” or “multiple of the central value ”. The average value to which one refers here is therefore the median or the central value and not the mean value .
application
The MoM value can be used wherever a comparison of the direct measured values does not lead to a meaningful result. This is particularly true of individual measured values that change systematically over time.
Application example
If a pregnant woman wants to compare her personal AFP laboratory value with an ideal value, it makes no sense to use the average value for an entire period as a reference, for example the average AFP concentration between the 15th and 20th week of pregnancy. If one depicts the systematically increasing course of the AFP concentrations over this period, it becomes clear that a comparison only makes sense for the respective point in time of pregnancy in which the pregnant woman is. A woman in the 15th week compares her value sensibly with the reference value of the 15th week in the adjacent figure: If her AFP concentration in the 15th week were exactly 22 IU / ml, the MoM value would be 1 (the simple of the median). At an AFP concentration of 44 IU / ml the MoM value would be 2 (twice the median) and at an AFP concentration of 11 IU / ml the MoM value would be 0.5 (half the median). In another week of pregnancy, the MoM values would be for other concentrations. For example, in the following 16th week, 1 MoM would correspond to a concentration of 28 IU / ml, 2 MoM to 56 IU / ml and 0.5 MoM to 14 IU / ml.
Areas of application
A focus for the use of MoM values can be found in the area of prenatal diagnostics . In the prenatal screening for chromosomal abnormalities and neural tube defects , in particular, direct measured values are never used in the risk calculation, but almost exclusively MoM values or their logarithms . The mathematical use of such MoM values in this form of risk analysis is well-founded and described in detail by Palomaki and Haddow as well as by Reynolds and Penney.
Individual evidence
- ↑ Palomaki GE, Haddow JE. Maternal serum alpha-fetoprotein, age, and Down syndrome risk. At J Obstet Gynecol. 1987 Feb; 156 (2): 460-3, doi : 10.1016 / 0002-9378 (87) 90309-7
- ^ Reynolds ™, Penney MD. The mathematical basis of multivariate risk screening: with special reference to screening for Down's syndrome associated pregnancy. Ann Clin Biochem . 1990; 27 (5): 452-8, doi : 10.1177 / 000456329002700506