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Stats Chapter 6
Normal Probability Distributions
Term | Definition |
---|---|
Normal probability distribution | Distribution of probabilities that plots all of its values in a symmetrical fashion and most of the results are situated around a probability's mean; values are equally likely to plot above or below the mean |
What types of variables have a normal or an approximately normal distribution? | Continuous random variables (weight) and Discrete random variables (score from test with set number of questions) |
What are the first 2 properties of the standard normal distribution? | 1) The total area under the normal curve is equal to 1. 2) The distribution is mounded and symmetrical; it extends indefinitely in both directions, approaching but never touching the horizontal axis |
What are the other 3 properties of the standard normal distribution? | 3) The distribution has a mean of 0 and a standard deviation of 1 4) The mean divides the area in half (0.50 on each side) 5) Nearly all the area is between z - -3.00 and 3.00 |
Standard normal distribution | The normal distribution of the standard variable z |
The standard normal distribution is also known as... | Standard score Z-score |
Binomial distribution | Probability distribution of the discrete random variable x, the number of successes observed in "n" repeated trials; as "n" trials becomes larger, the probability distribution appears more normal |
What is the main difference between the binomial and normal probability distribution? | Binomial: random variable is discrete Normal: random variable is continuous |
Continuity Correction Factor | Addition and subtraction of 0.5 to the x-value to convert a discrete random variable into a continuous one |
Mean in a binomial distribution | u = np |
Standard deviation in a binomial distribution | o = sqrt(npq) |
Rule for binomial distribution | normal distribution provides a reasonable approximation to a binomial probability whenever the values of np and n(1-p) both equal or exceed 5. |