THE PROMISE AND THE PRODUCT 499 So much is this so, that it is not too big a stretch to regard a toiletries R & D laboratot•v as being composed of a central evaluation group to which are attached subsidiary basic science and product development services. Such an attitude would rarely be reflected in the organization structure of a laboratory, but nevertheless may permeate its philosophy and be made visible in its publications, both internal to the business and external to the world outside. Indeed in the enlightened climate of to-day, it is necessary and right that the external face of our science show itself in this way. 'Science is good, more science is better' has been succeeded already by 'science is good, so what?' and we want now to make it clear that 'science is good because .... ' This is the philosophy we hope to achieve in Unilever, but we are only mortal and I shall now try and expose our frailty and some of our strengths. THE PRACTICE OF EVALUATION Physical evaluation of functional performance Let us accept that products which claim or imply a specific functional performance must perform. And that for such products, this performance is the prime criterion by which they will be judged. A hair colourant must colour hair--or else what is it? In rather closer definition, it is necessary to evaluate in the terms of physical science, the degree of performance of a product which claims or implies a performance measurable in terms of physical science. By the ethical standards of to-day--and perhaps society has improved in some respects, if not all--we believe a product should meet its claims and that these claims should relate to the user's needs. The well-informed, critical society in which we operate will help to keep our ethics bright and shining, but we too must be on our guard against worship of false technical gods, since psychological and emotional satisfactions are also real and some- times sadly underestimated. The requisites for a satisfactory physical evaluation technique are numerous and, ideally, stringent: The effect/phenomenon measured must be in 1: 1 correspondence with that understood by the user to be claimed. The technique be must reproducible,

500 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS The discrimination must adequate. The conditions under which the test is carried out must be realistic. If all these are met and the product survives, then: The technique should be published so as itself to survive peer judgment. which can result in: The technique is accepted as a national or international standard by which we and our competitors will be judged. This catalogue is severe, but I believe more widely achievable than generally realized. The outstanding example is probably in the dental field with reduction of caries incidence, where because the evaluation problem is so difficult, but the goal so worthwhile, the research resource expended by the industry has been by any standard vast. It was recognized early that what- ever laboratory methods might be available for mechanistic screening, the ultimate test must be in use, over long periods, and with large numbers of subjects to cope with biological variations. Research workers tried a variety of protocols, all subject to one or another flaw, either procedural or statistical. Eventually, and with not a little prompting from some of us, an inter- national working party of leading clinicians produced a definitive protocol for the conduct of such trials, which is kept under constant review (1). Improvements are still being made to the statistical treatments so that even more information can be extracted from these very expensive and time- consuming trials. Unfortunately agreement has not yet been reached as to how the results of such trials are to be presented to the public and there is a real difficulty in communicating such a complex set of data without either inadvertently misleading, or only conveying ineffective generalities. To quote Horowitz et al. (1). 'The practice of presenting results as percentage reductions may be misleading. In the interpretation of proportional caries scores, it is essential to pay equal attention to the numerator and denominator of the scores. For example, if the mean increment of new carious surfaces in the control group is only 0.5 per child, and if in the test group the corresponding value is 0.25 per child, this represents percentage reduction of 50•o. There has only been, however, a saving of 0.25 carious surfaces per child. One must