Targeting assessment responses

Overall coherence is an important alternative to the above measures when it is wished to assess the similarity between target and response waveforms but there is a substantial delay between them. It provides an estimate of the proportion of the response that is correlated with the target over all frequencies [ O Dwyer and Neilson, 1995 O Dwyer et al., 1996]. 

Other approaches have been used to estimate nutrient requirements, such as metabolic balance studies and nutrient analysis of human milk. However, both of these approaches adopt an arbitrary target value to assess response to various nutrient intakes. For the premature infant, whose actual existence outside the womb is unnatural , it is impossible, other than by arbitrary definition, to define and justify goals. Therefore, although the intrauterine accretion data are based on relatively few observations and may be an underestimate of true intrauterine accretion, they presently represent the most appropriate guideline for establishing minimum growth and nutrient accretion goals in the newborn premature infant. 

Accounting for the Behavioral Responses of Recipients. Ideally, a targeting assessment should rank households by their level of income or consumption in the absence of the program. Only then, when the analyst knows how poor program beneficiaries would have been without the program, can he or she estimate the true incidence of the benefits. The problem is, of course, that direct observation of what recipients welfare would have been in the absence of the program is not possible, and so some approximation of it must be made. 

Variability arises from true heterogeneity in characteristics such as dose-response differences within a population, or differences in contaminant levels in tlie enviromiient The values of some variables used in an assessment change witli time and space, or across tlie population whose exposure is being estimated. Assessments should address tlie resulting variability in doses received by members of the target population. Individual exposure, dose, and risk can vary widely in a large population. The central tendency and high end individual risk descriptors are intended to capture tlie variability in exposure, lifestyles, and other factors tliat lead to a distribution of risk across a population. 

Superficial chemical peels, including salicylic and glycolic acids, and Jessner s peels target the stratum corneum to the papillary dermis. These agents can be safely used to facilitate the resolution of PIH (Figs. 16.2,16.3,16.4 and 16.5). To assess for variability in response and limit further PIH, when possible, chemical peels should be initiated at the lower concentrations and titrated to higher concentrations if necessary to increase efficacy while minimizing side effects (see Darker Skin Section). 

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