S = { − log ⁡  10   ℙ ( N ≥ N obs   )   if  N obs   ≥ E [ N ]    log ⁡  10   ℙ ( N ≤ N obs   )   if  N obs   < E [ N ]             ( 2 )    MathType@MTEF@5@5@+=feaafiart1ev1aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacH8akY=wiFfYdH8Gipec8Eeeu0xXdbba9frFj0=OqFfea0dXdd9vqai=hGuQ8kuc9pgc9s8qqaq=dirpe0xb9q8qiLsFr0=vr0=vr0dc8meaabaqaciaacaGaaeqabaqabeGadaaakeaacqWGtbWucqGH9aqpdaGabeqaauaabiqaciaaaeaacqGHsislcyGGSbaBcqGGVbWBcqGGNbWzdaWgaaWcbaGaeGymaeJaeGimaadabeaatuuDJXwAK1uy0HMmaeHbfv3ySLgzG0uy0HgiuD3BaGabaOGae8xgHaLaeiikaGIaemOta4KaeyyzImRaemOta40aaSbaaSqaaiabb+gaVjabbkgaIjabbohaZbqabaGccqGGPaqkaeaacqqGPbqAcqqGMbGzcqqGGaaicqWGobGtdaWgaaWcbaGaee4Ba8MaeeOyaiMaee4CamhabeaakiabgwMiZkab=ri8fjabcUfaBjabd6eaojabc2faDbqaaiGbcYgaSjabc+gaVjabcEgaNnaaBaaaleaacqaIXaqmcqaIWaamaeqaaOGae8xgHaLaeiikaGIaemOta4KaeyizImQaemOta40aaSbaaSqaaiabb+gaVjabbkgaIjabbohaZbqabaGccqGGPaqkaeaacqqGPbqAcqqGMbGzcqqGGaaicqWGobGtdaWgaaWcbaGaee4Ba8MaeeOyaiMaee4CamhabeaakiabgYda8iab=ri8fjabcUfaBjabd6eaojabc2faDbaaaiaawUhaaiaaxMaacaWLjaWaaeWaaeaacqaIYaGmaiaawIcacaGLPaaaaaa@815C@