Karen was working the day shift in the hematology laboratory. The laboratory’s protocol called for three levels of blood cell controls to be run at the following times: (1) at the beginning of the shift, (2) within each run of patient samples during the day, and (3) any time reagents were changed. The mean for the low (abnormal) control for the red blood cell count was given as 2.00 3 1012/L, the standard deviation was 0.15, and the confidence limit (acceptable control range) was 2.00 3 1012/L 6 2 s (or 6 0.3).The first morning low control result was 2.10 (3 1012/L). In five subsequent runs, the low control re-sults were 2.16, 2.19, 2.20, 2.22, and 2.25.   1.These values represent:  a shift b.a trend c.neither shift nor trend 2.Should Karen be concerned about these values? Explain. 3.does Karen need to take any action?

Definition Definition Measure of central tendency that is the average of a given data set. The mean value is evaluated as the quotient of the sum of all observations by the sample size. The mean, in contrast to a median, is affected by extreme values. Very large or very small values can distract the mean from the center of the data. Arithmetic mean: The most common type of mean is the arithmetic mean. It is evaluated using the formula: μ = 1 N ∑ i = 1 N x i Other types of means are the geometric mean, logarithmic mean, and harmonic mean. Geometric mean: The nth root of the product of n observations from a data set is defined as the geometric mean of the set: G = x 1 x 2 ... x n n Logarithmic mean: The difference of the natural logarithms of the two numbers, divided by the difference between the numbers is the logarithmic mean of the two numbers. The logarithmic mean is used particularly in heat transfer and mass transfer. ln x 2 − ln x 1 x 2 − x 1 Harmonic mean: The inverse of the arithmetic mean of the inverses of all the numbers in a data set is the harmonic mean of the data. 1 1 x 1 + 1 x 2 + ...