Chapter 6: Part 1 Flashcards
What do normal probability distributions allow us to make?
Inferences about all kinds of data
What have mathematicians determined about normal distributions?
That they follow regular patterns, and by knowing the characteristics we can make inferences about data
What can we use the standard normal table to determine?
The z-score that marks off a certain proportion of a population
What can the normal distribution be used in place of?
The binomial distribution to determine probabilities when there are large numbers of observations
What does a values position on the chart indicate?
Where a data point is relative to the others, both in terms of the value itself, but also in terms of frequency
What will the distribution chart for any variable have?
Values and units of the variable on the x-axis and the frequency on the y-axis
What does a normal distribution tell us for any particular value of the variable?
How common the value is, how far it is from the mean (above or below)
What does the mean define?
Where the center of each distribution will be
What does the standard deviation define?
The spread of the distribution
What do narrower distributions have?
Smaller standard deviations
What do wider distributions have?
Larger standard deviations with more variability among the values
What is the formula for standard deviation?
o = square root o^2 (square root of the variance)
What are the three properties of a normal curve?
Symmetric about the mean, all three measures of central tendency are the same, proportion of areas between the standard deviations are known
What do the three properties of a normal curve create?
Family resemblance among the distributions of all variables that are normally distributed
In a normal curve what are the sections of the normal curve defined by the standard deviation?
The same regardless of the value of the standard deviation