AP Stats Ch. 2 Vocab

Question 1

Percentile

Answer 1

the pth percentile of a list is the smallest number such that at least p% of the numbers are no larger than it

Question 2

Cumulative Relative Frequency Graph

Answer 2

allows an examination of location within a distribution. observations are grouped into equal width classes with percents on the y-axis

Question 3

Z-Scores

Answer 3

standardized value; number of standard deviations away an observation is. Z= x-mean/standard deviation

Question 4

Transforming Data

Answer 4

Add/Subtract: -measurements of center & location (median, mean, quartiles, percentiles) increase or decrease by X.

Mult/Divide: measurements of center & location change by x, while measurements of spread change by the absolute value of x.

Nothing changes shape.

Question 5

Density Curve

Answer 5

always remains on or above x-axis and has a total area of 1 underneath. area= proportion of observations

Question 6

Median of Density Curve

Answer 6

same as mean

Question 7

Mean of Density Curve

Answer 7

middle value

Question 8

Standard Deviation of a Density Curve

Answer 8

amount away from the mean; 3 standard deviations fit in the typical normal density curve

Question 9

Normal Curves

Answer 9

bell curves

Question 10

Normal Distributions

Answer 10

described by a special family of bell shaped symmetric density curves (normal curves). Mean & standard deviation specify N(mean,Sx)

Question 11

68-95-99.7 Rule (Empirical Rule)

Answer 11

describes what percent of observations lie within 1,2, and 3 standard deviations

Question 12

Standard Normal Distributions

Answer 12

mean = 0; Sx = 1

Question 13

Normal Probability Plot

Answer 13

used to asses normality. if points lie in a somewhat straight line, data is normal.