Biostatistics course Part 5 Binomial distribution Dr en

Biostatistics course Part 5 Binomial distribution Dr. en C. Nicolás Padilla Raygoza Facultad de Enfermería y Obstetricia de Celaya Universidad de Guanajuato México

Biosketch n Medical Doctor by University Autonomous of Guadalajara. n Pediatrician by the Mexican Council of Certification on Pediatrics. n Postgraduate Diploma on Epidemiology, London School of n n Hygine and Tropical Medicine, University of London. Master Sciences with aim in Epidemiology, Atlantic International University. Doctorate Sciences with aim in Epidemiology, Atlantic International University. Associated Professor B, School of Nursing and Obstetrics of Celaya, university of Guanajuato. padillawarm@gmail. com

Competencies n The reader will define what is binomial distribution. n He (she) will know how is binomial distribution.

Introduction n We know how calculate single probabilities, but now, we have to calculate more complex probabilities. n Example n 100 new born in a maternity in Celaya. 55 were females and 45 were males. Probability to be girl was 55/100 = 0. 55 Probability to be boy, was 45/100=0. 45 n n What is the probability of two males in the next three new borns in this maternity?

Introduction n Two males between three new borns can occur: n n n Male Female (MMF) Male Female Male (MFM) Female Male (FMM) n A, B and C are mutually excluded, and Probability (HHM) + Probability (HMH) + Probability (MHH)

Introduction n What is the probability that at least 1 of the next three new born be male? n The combinations: n MFF, FMF, FFM, MMF, MMM. To calculate probability in each combination and then add them, consume time. n The possible combinations of gender in three new born are 8: MFF, FMF, FFM, MMF, MMM, FFF. n

n In anyone calculation of probability, we should count how many combinations of an event will produce an result; to calculate the probability of each combination and then add the probability of all combinations, because they are mutually excluded.

Binomial distribution n Describe probability of a characteristic that only can take two values.

Bibliografía n 1. - Last JM. A dictionary of epidemiology. New York, 4ª ed. Oxford University Press, 2001: 173. n 2. - Kirkwood BR. Essentials of medical ststistics. Oxford, Blackwell Science, 1988: 14. n 3. - Altman DG. Practical statistics for medical research. Boca Ratón, Chapman & Hall/ CRC; 1991: 1 -9.