Unit of comparison

These sections include brief discussions of statistics, data presentation, and terminology. The two major points regarding statistics are that the litter (or mating pair) is the unit of comparison, and that significance tests can be used only as a support for the interpretation of results—the interpretation itself must be based on biological plausibility. That the litter is the unit of comparison is a guiding principle ofvirtually all texts on the subject (e.g., see ref 7). It should be stated that this guideline does not require that statistical analyses be performed on every study. It is implied that statistical analyses should be used as a tool for interpretation. 

As part of protocol development, the choice of statistical analyses should be made a priori although specific additional analyses may be appropriate once the data are collected. The unit of comparison is the pregnant female or the litter and not individual fetuses as only the dams are independently and randomly sorted into dose groups. The fetus is not an independent unit and cannot be randomly distributed to groups. Intralitter interactions are common for a number of parameters, for example, fetal weight or... 

Non-coagulable nitrogen (taking for unit of comparison that formed at 16°) 100 151 8 159 9 147 6... 

Morphine, with a half-life of 3 hours, is the basic unit of comparison other drugs are compared to morphine. Morphine 1 mg hydromorphone 0.2 mg fentanyl 50 pg meperidine 10 mg. 

Figure 1 Comparison of two electrolysis units of different maximum current and different response.

Cp is tire number of elasticity active chains per volume unit. The comparison between experimental data and tire prediction by (C2.1.20) shows a reasonable agreement up to large defonnation (figure C2.1.16). For large values of X, strain hardening arises because of tire limited extensibility of tire chains or because of shear-induced crystallization. 

Note that we are interested in nj, the atomic quantum number of the level to which the electron jumps in a spectroscopic excitation. Use the results of this data treatment to obtain a value of the Rydberg constant R. Compare the value you obtain with an accepted value. Quote the source of the accepted value you use for comparison in your report. What are the units of R A conversion factor may be necessary to obtain unit consistency. Express your value for the ionization energy of H in units of hartrees (h), electron volts (eV), and kJ mol . We will need it later. 

Plot E versus log t for both of these sets of data on the same graph. Now suppose that the units of the 45°C experiment are minutes instead of seconds (this is not the case, but we can pretend that it is). On the basis of this imaginary condition, each of the times at 45°C should be multiplied by the factor 60 sec/min to make the comparison with the 25°C data. Apply this correction to the 45°C data and plot on the original graph. Be sure to select a scale of the original graph so that corrected data can be accommodated also, label various portions clearly. Briefly comment on the results of this manipulation. 

Color. Many water samples have a yellow to brownish-yeUow color which is caused by natural substances, eg, leaves, bark, humus, and peat material. Turbidity in a sample can make the measurement of color uncertain and is usually removed by centrifiigation prior to analysis. The color is usually measured by comparison of the sample with known concentrations of colored solutions. A platinum—cobalt solution is used as the standard, and the unit of color is that produced by 1 mg/L platinum as chloroplatinate ion. The standard is prepared from potassium chloroplatinate (K PtCl ) and cobalt chloride (C0CI26H2O). The sample may also be compared to suitably caUbrated special glass color disks. 

Physical Properties. Physical properties include specific gravity, water absorption, mold shrinkage, transmittance, ha2e, and refractive index. Specific gravity affects performance and has commercial implications. The price of the material divided by the specific gravity gives the yield in cost per unit volume. Comparison of yields gives an evaluation of raw material costs. 

To design an air recirculation system it is necessary to know the performances of fans, air cleaners, and exhaust hoods included in the current system. The equations described here include the source generation rate and the total airflow rate through the room, which could be difficult to measure. The ratio between source rate and flow rate has the unit of concentration and should in fact be equal to the concentration without recirculation. The equations could thus be transformed to include the contaminant concentration without recirculation instead of this ratio. In this way a direct comparison between concentration without and with recirculation is possible. By using the described equations it is then possible to design an air recirculation system to result in the demanded concentration in a workroom. 

Systematic error, as stated above, can be eliminated— not totally, but usually to a sufficient degree. This elimination process is called calibration. Calibration is simply a procedure where the result of measurement recorded by an instrument is compared with the measurement result of a standard. A standard is a measuring device intended to define, to represent physically, to conserve, or to reproduce the unit of measurement in order to transmit it to other measuring instruments by comparison. There are several categories of standards, but, simplifying a little, a standard is an instrument with a very high accuracy and can for that reason be... 

The ionization energy is given in this book in units of kilocalories per mole, the energy that would be required to remove an electron from each one of a mole of atoms. These units allow an easy comparison between ionization energies and the energy changes that occur in ordinary chemical reactions. 

For scientific work the fundamental standard of mass is the international prototype kilogram, which is a mass of platinum-iridium alloy made in 1887 and deposited in the International Bureau of Weights and Measures near Paris. Authentic copies of the standard are kept by the appropriate responsible authorities in the various countries of the world these copies are employed for the comparison of secondary standards, which are used in the calibration of weights for scientific work. The unit of mass that is almost universally employed in laboratory work, however, is the gram, which may be defined as the one-thousandth part of the mass of the international prototype kilogram. 

Fig. 1.14. Comparison of the MD calculations of the correlation functions of the translational velocity and angular momentum in liquid nitrogen [65]. The time is in units of 10-13 s.

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