STAT 2120 Binomial Distribution

LEC 12

Probability model

mathematical description of a random phenomenon consisting of

1. sample space

2. method of asssigning probabilities to events

• can be discrete or continuous based on how countable sample space is

Discrete probability models presented as tables/assign probability to each possible outcome

probabiltiy MUST be between 0 — 1

sum of all outcome probabilities MUST be equal to 1

Random variable

variable that records numeric outcomes of a random phenomenon

Probability districbution

probability model for a random variable

Binomial setting

discrete probability distribution occurs when the outcome of a random phenomenon is a count

Binomial distribution requirements

1. fixed number of observations or trials “n”

2. observation are independent of one another

3. observations have 2 possible values (success or failure) ; doesn’t consider qualitative success

4. probabilty of a sucess if the same “p” for each “n” observations

• probability of failure = 1- p for each observation