Beta-level

As an example, we can set alpha- and beta- levels to the same value, which makes for a simple computation of the number of samples needed, at least for the simple case we have been considering the comparison of means. If we use the 95% value for both (a very stringent test), which corresponds to a Z-value of 1.96 (as we know), then if we let D represent the difference in means between the two values (sample data and population mean), and S is the precision of the data, we find that... 

The screen must be very sensitive in its detection of potential effective agents. An absolute minimum of active agents should escape detection that is, there should be very few false negatives (in other words, the type II error rate or beta level should be low). Stated yet another way, the signal gain should be way up. 

Type II Error (false negatives) Concluding there is no effect when there really is an effect. Its probability is the beta level... 

Levin-AUerhand, J.A., Lominska, C.E., Smith, J.D. (2002) Increased amyloid-beta levels in APPSWE transgenic mice treated chronically with a physiological high-fat high-cholesterol diet. J. Nutr. Health Aging, 6, 315-319. 

Berry A, Tomidokoro Y, Ghiso J, Thornton J (2008) Human chorionic gonadotropin (a luteinizing hormone homologue) decreases spatial memory tmd increases brain amyloid-beta levels in female rats. Horm Behav 54 143-152... 

Lemere CA, Beierschmitt A, Iglesias M, Spooner ET, Bloom JK, Leverone JE, Zheng JB, Seabrook TJ, Louard D, Li D, Selkoe DJ, Paknour RM, Ervin ER (2004) Alzheimer s disease a beta vaccine reduces central nervous system a beta levels in a non human primate, the Caribbean vervet. Am J Pathol 165(l) 283-297. 

Beach TG, Kuo YM, Schwab C, Walker DG, Roher AE. 2001. Reduction of cortical amyloid beta levels in guinea pig brain after systemic administration of physostigmine. Neurosci. Lett. 310 21-24... 

Cirrito J, Yamada K, Finn M et al (2005) Synaptic activity regulates interstitial fluid amyloid-beta levels in vivo. Neuron 48 913-922... 

Esslimani-Sahla M, Simony-Lafontaine J, Kramar A, et al. Estrogen receptor beta (ER beta) level but not its ER beta cx variant helps to predict tamoxifen resistance in breast cancer. Clin Cancer Res. 2004 10 5769-5776. 

The relative value placed upon avoiding Type I and Type II errors can be appreciated by examining the ratio of beta level to alpha level at sample sizes generally seen in the lead literature. Table 1, taken from a recent communication by Rosenthal and Rubin (1985), is informative. It shows that for a sample size between 80 and 200, at an r of 0.10, the ratio of accepted beta to alpha error can be as high as 17 to 1. 

Procedures of the beta-galactosidase activity measuring using colour reaction with ONPG and X-Gal without cells permeabilization were developed and the detection limit at the level of 4 ppb has been achieved. The influence of the foreign ions (phosphate, sulphate, carbonate et. al) was studied. 

Ullum, H., Lepri, A. C., Victor, J., Aladdin, H., Phillips, A. N., Gerstoft, J., Skinhoj, P., and Pedersen, B. K. (1998). Production of beta-chemokines in human immunodeficiency virus (HIV) infection Evidence that high levels of macrophage in inflammatory protein-1-beta are asociated with a decreased risk of HIV progression. J. Infect. Dis. 177 331-336. 

---