Location, effect

Sullivan AP, Dashwood MR, Dickenson AH (1987) ai adrenoceptor modulation of nociception in rat spinal cord location, effects and interaction with morphine. Eur J Pharmacol 138 169-177... 

Lfg m Effective length of vessel where separation occurs, ft (To allow for inlet turbulence and outlet nozzle location, effective length can be approximated as at 0.75 timet the seam-to-team length, LM)... 

Box and Meyer (1986) considered the identification of dispersion effects in unreplicated 2k p designs. The first step in their approach is to identify and estimate the active location effects. Let r,(i = 1,..., ) denote the residuals from the fitted location model. To examine whether factor j has a dispersion effect (or, equivalently, whether there is a dispersion effect associated with the jth main effect contrast), compute the sums of squared residuals at the two levels of this factor ... 

Box and Meyer also derived a useful result (which is applied in some of the subsequent methods in this chapter) that relates dispersion effects to location effects in regular 2k p designs. We present the result first for 2k designs and then explain how to extend it to fractional factorial designs. First, fit a fully saturated regression model, which includes all main effects and all possible interactions. Let /3, denote the estimated regression coefficient associated with contrast i in the saturated model. Based on the results, determine a location model for the data that is, decide which of the are needed to describe real location effects. We now compute the Box-Meyer statistic associated with contrast j from the coefficients 0, that are not in the location model. Let i o u denote the contrast obtained by elementwise multiplication of the columns of +1 s and—1 s for contrasts i and u. The n regression coefficients from the saturated model can be decomposed into n/2 pairs such that for each pair, the associated contrasts satisfy i o u = j that is, contrast i o u is identical to contrast j . Then Box and Meyer proved that equivalent expressions for the sums of squares SS(j+) and SS(j-) in their dispersion statistic are... 

The main advantage of the McGrath-Lin (2001) statistic is reduced confounding when multiple dispersion effects are present. There are also several drawbacks. The statistic is complicated to compute and may be applicable only to a subset of the main effects and interactions in the design. For example, McGrath and Lin (2001) presented a 25 1 experiment with four active location effects. Eight potential... 

Holm and Wiklander (1999) presented test statistics for dispersion effects derived from quadratic functions of the location effects. These test statistics are equivalent to the Box and Meyer (1986) statistics. The Holm and Wiklander version emphasizes how they can be seen as correlation coefficients among the null location effects, which can be used as a basis for making statistical inferences about possible dispersion effects. 

Correct identification of the location model is a serious problem that affects all the methods for identifying and estimating dispersion effects. Pan (1999) showed that small to moderate location effects that are undetected can seriously impair... 

McGrath and Lin (2002) suggested examining the contribution of each pair of coefficients to D M as an effective diagnostic check. For example, one can then detect if just one pair of borderline location effects is responsible for a putative dispersion effect. 

One might try to correct for the problems caused by moderate location effects by just fitting a larger location model. However, expanding the location model may leave too few degrees of freedom in the residuals to enable identification of dispersion effects. 

Pan, G. (1999). The impact of unidentified location effects on dispersion effects identification from unreplicated factorial designs. Technometrics, 41, 313-326. 

Chronic pain is often a source of tremendous frustration for patients, family members, and health care professionals. Patients with these problems are often tireless in their pursuit of pain relief. When relief is elusive, patients and their family members can experience severe hopelessness and express rage at the medical profession for failing to locate effective treatments. Health care professionals share this helplessness even as they continue to put forth their best efforts to find pain relief (Turk, 1996). 

Nucleotide position Location Effect Allelic frequency Expression mRNA/pro tein Probe drug phenotype... 

The problems of P-lactam and quinolone resistance in Neisseria gonorrhoeae are increasing, and selection of a particular drug will depend on sensitivity testing and a knowledge of resistance patterns in different geographical locations. Effective treatment... 

Even without evidence that location effects are a concern, consideration of experimental units (details in the next paragraph) may lead to assay designs (and associated analyses) that will provide good protection against location effects. In most assay laboratories, samples are assigned to plate rows (or columns) and sample concentrations are assigned to plate columns (or rows). Often a multichannel pipette is used to dilute multiple samples simultaneously. 

Aroclor 1254 for durations as short as 1-3 days (Bruckner et al. 1977) no other hepatic end points were evaluated in this study. Relative liver weight and serum total cholesterol were increased in rats that were fed estimated doses of i mg/kg/day Aroclor 1254 for 4 days, but not 0.5 mg/kg/day (Carter 1984, 1985) histology was not evaluated. Acute-duration studies evaluating hepatic effects of PCBs other than microsomal enzyme induction at doses lower than those in the Carter (1984, 1985) studies were not located. Effects in rats exposed to higher doses of PCBs in acute-duration studies included increased liver weight, decreased Uver glucose 6-phosphatase, and/or decreased serum cholesterol at... 

AF3 64606 Location Effect Functional Consequences Frequency Reference... 

Should it occur that the premises are unsuitably located, effective measures should be taken to avoid such contamination. 

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