Median array

Median is the middle value of the Monte Carlo simulation data when they are sorted from low to high. In other words, 50% of the data is less than the median. If there is an even number of data points, then the median is the average of the middle two points. In spreadsheet, the sample mean = Average (array) and the sample median = Median (array). 

The median or 50th percentile = Quartile (array, 2) or =Median(array). 

Fig. 3.35 Median of the resistances belonging to the 38 sensor segments of the gradient micro-array during a meeting of 18 people in a room of 258 m3 without ventilation and with the windows closed for most of the time. The height of the ceiling is 2.80 m. The KAMINA was operated at the back of the room at a height of 1.0 m above the floor. Soon after...

Median BCF values in aquatic biota exposed to various concentrations of Pb+2 for 14 to 140 days varied from about 42 in fish to 2570 in mussels intermediate values were 536 for oysters, 500 for insects, 725 for algae, and 1700 for snails (USEPA 1985). There are several notable exceptions to this array significantly higher values have been reported in crustacean hepatopancreas (Heyraud and Cherry 1979), in various species of freshwater invertebrates (Spehar et al. 1978), in fish bone (Demayo et al. 1982) and liver (Haux and Larsson 1982), and in whole oysters (Zaroogian et al. 1979). In oysters, for example, BCF values varied from 3450 to 6600 after exposure to solutions... 

The symbol X is the symbol used for the sample mean. It is an estimate of the value of the mean of the underlying population, which is designated i. We can never determine 11 exactly from the sample, except in the trivial case where the sample includes the entire population but we can quite closely estimate it based on sample mean. Another average that is frequently used for measures of location is the median. The median is defined as that observation from the sample that has the same number of observations below it as above it. Median is defined as the central observation of a sample where values are in the array by sizes. 

FIGURE 5 Relative scopes (measured as quartile range/median) for an array of extracellular enzymes and for bacterial production and respiration. Dependent variables shown along the X-axis are (left to right) leucine aminopeptidase, phosphatase, fatty acid esterase, (3-glucosidase, a-glucosidase, bacterial production, and bacterial respiration. Data are derived from four DOM experimental amendments. 

Finally, a median-based exclusion algorithm has been applied to data obtained with a fully implanted array of four microelectrochemical sensors.38,39 The Z-score was calculated from the values of individual sensors and the median absolute deviation, as shown in equation (8.11), and sensor readings were removed from the data set if the value was greater than one. 

Ward WK, Casey HM, Quinn MJ, Federiuk IF, Wood MD. A fully implantable subcutaneous glucose sensor array enhanced accuracy from multiple sensing units and a median-based algorithm. Diabetes Technology Therapeutics 2003, 5, 943-952. 

One common microarray data normalization method is to calculate a normalization factor on a per array basis or across an entire experiment. The primary assumption for using a singular normalization factor is that the volume of labeled sample is comparable across the two channels. Thus, due to the large population of labeled cDNA within the uniform volume it is assumed that the same number of labeled cDNAs exist in both samples. Ideally, the overall intensity in the two channels will be the same. Furthermore, any increases in labeled cDNAs, due to increases in mRNA, must result in decreases of some other labeled cDNAs. Typical methods include mean- or median-centering, where the mean/median values are centered within the data distribution, and z-score normalization which adds a scaling factor to mean-centering. 

The dry lab portion of microarray analyses involves identifying the hybridized spots on the scanned tiff images (gridding) and defining the area and portion of the spot that should be quantified. Most often, mean or median pixel intensities for each spot are extracted from the tiff images. The result is a separate numeric value for each spot and each sample that represents the relative amount of sample hybridized to that spot. Thus, the raw results from an array experiment can be thousands... 

Corrosion rate values were calculated from the mass loss of each test presenting a statistical array and indicating corrosion rate ordered array average value v, mode value vmode, median value vmediam and standard deviation s. 

There are many variations on this particular type of normalization, including scaling the individual intensities so that the mean or median intensities are the same within a single array or across all arrays, or using a selected subset of the arrayed genes rather than the entire collection. 

Figure 13.1 Mean-difference smooth scatterplot for each array (log base 2). For each array, the mean and difference are computed using the intensity of the array studied and the intensity of a pseudoanay, which is constracted to have the median value, across all arrays, for each probe. We expect to see values are concentrated along the M = 0 line, since the majority of genes are not differentially expressed. P attems, such as trends, are indicative of potential problems.

Median me-de-9n n. The value in an arrayed set of repeated measurements that divides the set into two equal-numbered groups. If the sample size is odd, the medium is the middle value. The median is a useful measure of the center when the distribution is strongly skewed toward low or high values. Compare arithmetic mean. 

The edge preserving median filter is where the median value of the black pixels and gray pixels is computed in a 5x5 array, these two values and the central original brightness value are ranked in ascending order. A final median value is selected to replace the central pixel. This filter preserves edges and comers. 

Using the replicate data, determine the mean of the median net pixel intensities for each arrayed protein this is then the data to use in subsequent analyses. 

The lEUBK model employs a log-normal Pb input distribution and computational approach using calculations of geometric means from an assumption of intakes and biokinetics based on median values, and employs a GSD. The model presents a default GSD for a typical array of exposed children and also offers user-selected GSD choices. The choice of GSD is critical in such log-normal relationships as Pb exposures in human populations, since in applications for risk assessment the higher the GSD for a given typical child or typical children in an exposed population, the higher the fraction of individuals in the upper tail of the distribution and vice versa. 

Fig. 6 Multivariate scatter plots of gene expression in selected cell lines (A) and schematic representations of different expression patterns (B-D). The cases were normalized hy array median centering, with the median value of the gene expression in each case centered to zero and the standard deviation to one. The data analysis was performed hy Li Xiao (Eppley Institute for Research in Cancer, UNMC) using MATLAB software (The MathWorks, Inc.)...

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