Mean value median

Olive oil pigment Mean values Median values Range... 

Bones The reference values for the uranium content in adult human bones, calculated on the basis of the ash-weight, were reported for the mean value, median, and range of 12 14, 6.8, and 0.8-100 pg U kg- ashes, respectively (Tandon et al. 1998). The authors note that different approaches were adopted for this type of calculation so they used ashed bones as the basis for their estimate and comparison between different countries, and the median values for several countries are shown in Figure 4.20. 

Raw data are collected observations that have not been organized numerically. An average is a value that is typical or representative of a set of data. Several averages can be defined, the most common being the arithmetic mean (or briefly, the mean), the median, the mode, and the geometric mean. 

As shown by Examples 4.1 and 4.2, the mean and median provide similar estimates of central tendency when all data are similar in magnitude. The median, however, provides a more robust estimate of central tendency since it is less sensitive to measurements with extreme values. For example, introducing the transcription error discussed earlier for the mean only changes the median s value from 3.107eto3.112e. 

If the mean or median provides an estimate of a penny s true mass, then the spread of the individual measurements must provide an estimate of the variability in the masses of individual pennies. Although spread is often defined relative to a specific measure of central tendency, its magnitude is independent of the central value. Changing all... 

Errors affecting the distribution of measurements around a central value are called indeterminate and are characterized by a random variation in both magnitude and direction. Indeterminate errors need not affect the accuracy of an analysis. Since indeterminate errors are randomly scattered around a central value, positive and negative errors tend to cancel, provided that enough measurements are made. In such situations the mean or median is largely unaffected by the precision of the analysis. 

The data we collect are characterized by their central tendency (where the values are clustered), and their spread (the variation of individual values around the central value). Central tendency is reported by stating the mean or median. The range, standard deviation, or variance may be used to report the data s spread. Data also are characterized by their errors, which include determinate errors... 

Data point A numerical estimate of equipment reliability as a mean or median value of a statistical distribution of the equipment s failure rate or probability. 

When only a few measurements of a given property are available, and especially if an asymmetry is involved, the median is often more appropriate than the mean. The median, x , is defined as the value that bisects the set of n ordered observations, that is,... 

In particle size analysis it is important to define three terms. The three important measures of central tendency or averages, the mean, the median, and the mode are depicted in Figure 2.4. The mode, it may be pointed out, is the most common value of the frequency distribution, i.e., it corresponds to the highest point of the frequency curve. The distribution shown in Figure 2.4 (A) is a normal or Gaussian distribution. In this case, the mean, the median and the mode are found to fie in exactly the same position. The distribution shown in Figure 2.4 (B) is bimodal. In this case, the mean diameter is almost exactly halfway between the two distributions as shown. It may be noted that there are no particles which are of this mean size The median diameter lies 1% into the higher of the two distri-... 

Box plots, also known as box and whisker plots, are commonly used to display univariate statistics for a given variable across another variable. The statistics typically displayed in a box plot are the minimum, first quartile, median, third quartile, and maximum values. Mean values are often included in box plots as well. The following is a sample box plot of a clinical response measure showing how three different drug therapies compare to one another. 

Bpx extends to 25th and 75th percentile. Whiskers extend to minimum and maximum values. Mean values are represented by a dot while medians are connected by the line. 

If possible, the intake should be expressed both as a statistical mean or median and maximum (e.g., 95th percentile). Ideally, a frequency distribution of exposure for the study area population is the goal. Inmost cases, however, the variability in exposure medium intake rates and pollutant concentrations are unknown and average/maximum values must suffice. 

Mean value charts (charts on x, median charts, blank charts)... 

The mean values of the activity and aerosol median diameters together with the best estimate of the standard deviation, an, based on the total number of measurements made for each parameter, are listed in Table V. Figures 5-8 show representative size distributions ... 

In describing the average diameter of a sample, three parameters can be used the mean, the median, and the mode. The mean is the sum of all diameters divided by the total number of particles. It is sensitive to extreme values and thus is often not particularly useful. The median is the value above and below which 50% of the particles are found. It is less influenced by outlying values and is preferable to the mean as a single measure of particle size. The mode represents the size occurring most frequently it is used less frequently than the mean or the median. In a perfectly symmetrical distribution, the mean, median, and mode values are the same. 

The numerical difference, with respect to sign, between an individual result and the mean or median of the set. It is expressed as a relative or absolute value. 

Similar biomonitoring studies in Belgium and China conducted with adolescents (14—16 years) and children and students (3-24 years), respectively, showed a high detection frequency of more than 90% [154, 156]. However, mean and median values were lower compared to the US data. In the Chinese study, females had a statistically higher least square geometric mean concentration than males. They also observed a decreasing tendency with age in the 7-24 age group [156]. 

The three summary statistics are displayed in Figure 8.3. Clearly, for this data the mean and median are similar, and this is true for any distribution of values that is symmetric, which is the case here. The mode is somewhat removed from both the mean and median. In fact, the mode is not often used as a summary of data because it records only the most frequent value, and this may be far from the centre of the distribution. A second difficulty with the mode is that there can be more than one mode in a sample. For example, had one of the values 3.6 been instead 3.5, there would have been eight distinct modal values 3.3, 3.4, 3.6, 3.8, 4.0,4.1,4.4 and 4.7 mmol/L. 

Ten studies of nickel in human milk gave disparate results. Six median values ranged from 5 to 16 pg/L, and 10 mean values ranged from 1.5 to 39 pg/L (Iyengar 1989). Five of the six medians... 

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