L4: NPD

• When do we say that data are normally distributed?

  If the bars roughly follow a symmetrical bell or hill shape
• Most of the data values in a normal distribution tend to cluster around the mean.
• A bell curve has a small percentage of the points on both tails and the bigger percentage on the inner part of the curve.
• Normal Probability Distribution is also known as Gaussian distribution
• What are the characteristics of a normal curve?

  Symmetric bell

  Does not intersect or touch the horizontal axis (Asymptotic)

  Mean, median, and mode are equal

  The area under the normal curved is one or one hundred

  Mean = 0, standard deviation = one
• Skewness = refers to a distortion or asymmetry that deviates from the symmetrical bell curve, or normal distribution, in a set of data.
• It is a measure of the asymmetry of the probability distrbution of a real-valued random variable about its mean?

  Skewness
• If the curve is shifted to the left, or to the right, then it is sai dto be?

  Skewed
• The z-table helps by telling us what percentage is under the curve at any particular point.
• It tells us the area under the standard normal curve for any value between the mean (zero) and any z-score?

  Z-table