THE PROMISE AND THE PRODUCT 501 therefore critically look at the absolute values involved when one evaluates percentage reductions.' And I might say that similar comments can be made about all simple percentage-type reports, such as are used to communicate anti-perspirant effectiveness. These should relate to the scale of effect which the average consumer can in fact notice. In a very different field, consider hair sprays. As a result of background work and development, let us suppose that an improved product has been made which is designed to be superior to existing own and competitive brands in respect of: Easier brush-out. More efficient brush-out resulting in less build-up on the hair. Improved feel of the hair after brushing-out. Evaluation science can provide the evidence not so much to back a pre- conceived promise as to arrive at the promises which can confidently be made. The evaluation package would include: (2), (3) Combing resistance (instrumental techique). Curl retention ,, ,, ß Sensory assessment of brush-out and feel. Build-up (bench technique). The results are collected in a support package for the benefit of market- ing in its advertising development and relations with control authority. The need for consumer panels for independent uncontrolled judgment can never be, nor should be, eliminated by use of instrumental techniques or expert panels, even when applied to in-use situations. After all, the ulti- mate consumer panel is the market place and we expect to succeed in that most critical of all tests. Much has been published on operating techniques in this area and I do not intend to repeat this. However, such panels are particularly valuable, not only as a confirmation that the functionality sought and demonstrated in the laboratory does in fact survive, but also as a research tool for studying interaction terms otherwise inaccessible to the controlled experiments. Assessment techniques in development programmes Evaluation of functional performance in use calls for techniques and protocols based on the in-use situation and, where appropriate, which it

502 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS usually, is, accepting human variability, whether in physiology or manual aptitude. Furthermore judgement scales need to be tuned to real-life situa- tions and the nature of the promise 'twice as much lather' must mean as used with water at the recommended or likely temperature and generated by the hand of the user. The development chemist on the other hand in seeking improvements needs to identify trends so as to know quickly whether he is going uphill or downhill. He needs quick, highly discriminatory tests which above all will tell him whether he has a hope. He needs controlled conditions, no varia- bility, replication, speed and, preferably, economy. A further distinction is that whereas the whole product evaluation is customarily performed by a group established for this purpose--an evalua- tion section, which should stand as independent from the product developers as Internal Audit from Accounts--the assessment of development progress is usually done by the development scientist himself. He can accept a degree of artificiality, this depends on how well he under- stands the system. These tests are sometimes very dependent on assump- tions of mechanisms. But if a toothpaste with caries-reduction properties can only be evaluated by a 3-yr clinical trial, how can formulae be optimized within a lifetime? Only by making one or more hypotheses on best possible scientific bases concerning the mechanism, thus giving rise to techniques for assessing the relative effectiveness of formulae by discriminating between, e.g. fluorine uptakes on enamel or reduction in acid solubility of enamel or changes in plaque composition. Such tests can be quite rigorously standard- ized but the real criteria of value lie not with the standardization, however good, but with the validity of the hypotheses. An apparently simple area, also in the dental field, is still a matter of dispute, that is the abrasivity of dentifrices. The very hypothesis that there is an optimum abrasivity rests itself on a well-backed, yet still sometimes contested, view that some abrasion is essential to remove stain plus a view that very high abrasivity is potentially damaging. But abrading what? Enamel? Exposed dentine ? Acquired pellicle? Nevertheless a measure of agreement on assessment techniques (4, 5) has enabled progress to be made and, when coupled with cleaning assessment-- another very difficult subject--has resulted in the creation of improved dentifrices. Such assessment techniques have enhanced value and impor- tance to-day when it may be necessary to introduce new raw materials to formulae and retain the product properties desired. There are many other types of assessment process lying in this area of