Experiment replication

The need for good estimates of the variances of the measurements cannot be overemphasized. Unfortunately, these can be accurately estimated only by completely replicated experiments. 

The unmodified and complementary oligonucleotides were also synthesized, in order to detect thermodynamic and spectroscopic differences between the double helices. Circular dichroism spectra revealed that the covalently bound anthracene does not stack in the centre of the DNA double helix. Mutagenic activity by intercalative binding of the anthracene residue is thus unlikely. Only in vitro and in vivo replication experiments with site-specifically modified... 

Experimental Results. The inhibition of NDEIA formation after days at 37 forthree water-soluble and three oil-soluble inhibitors is displayed in Tables II and III, respectively. So that relative effectiveness could be compared, the concentration of each inhibitor was chosen to provide an inhibitor/nitrite mole ratio = 10, Each inhibitor was tested in two separate emulsion batches with two or more aliquots analyzed. The data shown for positive controls are from similar replicate experiments. 

Figure 4 Effect of temperature on the interfacial tension of an Alberta heavy oil in produced water containing LTS-18 surfactant. Data are from three separate replicate experiments conducted under the same conditions.

Hilarides and others (1994) investigated the destruction of TCDD on artificially contaminated soils using °Co y radiation. It appeared that TCDD underwent stepwise reduction dechlorination from tetra- to tri-, then di- to chlorodioxin, and then to presumably nonchlorinated dioxins and phenols. The investigators discovered that the greatest amount of TCDD destruction (92%) occurred when soils were amended with 25% water and 2% nonionic surfactant [alkoxylated fatty alcohol (Plurafac RA-40)]. Replicate experiments conducted without the surfactant lowered the rate of TCDD destruction. 

Figure 5.9 contains the same two replicate experiments shown in Figure 5.8, but here the response surface for the model y, = P jc, + r, is shown. The least squares solution is obtained as follows. 

If the model = 0 + r, does describe the true behavior of the system, we would expect replicate experiments to have a mean value of zero (y,- = 0) the sum of squares due to purely experimental uncertainty would be expected to be... 

If (and only if) replicate experiments have been carried out on a system, it is possible to partition the sum of squares of residuals, SS, into two components (see Figure 6.10) one component is the already familiar sum of squares due to purely experimental uncertainty, 55. the other component is associated with variation attributed to the lack of fit of the model to the data and is called the sum of squares due to lack of fit, SS. ... 

In Section 6.4, it was shown for replicate experiments at one factor level that the sum of squares of residuals, SS can be partitioned into a sum of squares due to purely experimental uncertainty, SS, and a sum of squares due to lack of fit, SSi f. Each sum of squares divided by its associated degrees of freedom gives an estimated variance. Two of these variances, and were used to calculate a Fisher F-ratio from which the significance of the lack of fit could be estimated. 

There remain two questions to be answered concerning the design of the experiments what five levels of pH should be chosen, and how should the replicate experiments be allocated among these five levels ... 

Given these five levels of pH, how can the five replicate experiments be allocated One way is to place all of the replicates at the center factor level. Doing so would give a good estimate of at the center of the experimental design, but it would give... 

In Figure 13.9, instead of carrying out four replicate experiments at the center point (as in Figure 13.2), the four replicates are carried out such that one experiment is moved to each of the existing four factorial points. The experimental design matrix is... 

In this design there are only six distinctly different factor combinations. Thus, there are no degrees of freedom for lack of fit when fitting a two-factor FSOP model with six parameters. There are three degrees of freedom for purely experimental uncertainty because of the four replicate experiments at the center point. 

Process variography provides verification whemer current TSE is below a priori determined, acceptable levels or not. For 0-D, this may be accomplished, for example by performing a replication experiment on me complete sampling procedure ten times (independently). It is essential mat replication mcludes all aspects of me current sampling process from primary samplmg to analytical result. McClellan and Kowalski [18] gives a brief delineation of me so-called replication experiment , which can be employed m me 0-D as well as in me 1-D domains. 

Exposed to 1,4-dichlorobenzene via gavage in corn oil at 300, 600, or 1000 mg/kg at 16 hrs before sacrifice for UDS experiment or at 96 hours before sacrifice for DNA replication experiment... 

It was also recognized that difficulties in conducting replicate experiments on a commercial scale were a problem that might be overcome through new systems to accurately deliver lower rates of O2 into smaller tanks (du Toit et ah, 2006a). 

Examining Figure 13, M is clearly way off the line. Also, A does not lie on the line but is unlikely to be significant. The question about MC is more difficult to answer but for the moment it is assumed that it not significant. This issue may be resolved, however, by conducting replicate experiments that provide an independent estimate of the residual error—this will be discussed later. 

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