Biostatistics course Part 5 Binomial distribution

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Biostatistics coursePart 5Binomial distribution

• Dr. en C. Nicolás Padilla Raygoza
• Facultad de Enfermería y Obstetricia de Celaya
• Universidad de Guanajuato México

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Biosketch

• Medical Doctor by University Autonomous of
  Guadalajara.
• Pediatrician by the Mexican Council of
  Certification on Pediatrics.
• Postgraduate Diploma on Epidemiology, London
  School of 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_at_gmail.com

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Competencies

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

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Introduction

• We know how calculate single probabilities, but
  now, we have to calculate more complex
  probabilities.
• Example
• 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 45/1000.45
• What is the probability of two males in the next
  three new borns in this maternity?

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Introduction

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

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Introduction

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

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• 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.

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Binomial distribution

• Describe probability of a characteristic that
  only can take two values.

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Bibliografía

• 1.- Last JM. A dictionary of epidemiology. New
  York, 4ª ed. Oxford University Press, 2001173.
• 2.- Kirkwood BR. Essentials of medical
  ststistics. Oxford, Blackwell Science, 1988 1-4.
• 3.- Altman DG. Practical statistics for medical
  research. Boca Ratón, Chapman Hall/ CRC 1991
  1-9.