Term
|
Definition
| elimination of units, standardized values can be compared and combined even if the original variables had different units and magnitudes |
|
|
Term
|
Definition
| a value found by subtracting the mean and dividing by the standard deviation |
|
|
Term
|
Definition
| adding a constant to each data value adds the same constant to the mean, the median, and the quartiles, but does not change the standard deviation or IQR |
|
|
Term
|
Definition
| Multiplying each data value by a constant multiplies both the measures of position (mean, median and quartiles) and the measures of spread (standard deviation and IQR) by that constant |
|
|
Term
|
Definition
| a useful family of models for unimodal, symmetric distribution |
|
|
Term
|
Definition
| a numerically valued attribute of a moel, for example, the values of µ and sigma in a N model are parameters |
|
|
Term
|
Definition
| a value calculated from data to summarize aspects of the data; for example, the mean and standard deviation |
|
|
Term
|
Definition
| a z-score tells how many standard deviations a value is from the mean; z-scores have a mean of 0 and a standard deviation of 1 |
|
|
Term
|
Definition
| a Normal model, N with mean µ = 0 and standard deviation = 1, also called standard Normal distribution |
|
|
Term
|
Definition
| a distribution is nearly Normal if it is unimodal and symmetric |
|
|
Term
|
Definition
| in a Normal model, about 68% of values fall within one standard deviation of the mean, about 95% fall within two standard deviations of the mean, and about 99.7% fall within three standard deviations of the mean |
|
|
Term
|
Definition
| the Normal percentile corresponding to a z-score gives the percentage of values in a standard Normal distribution found at that z-score or below |
|
|
Term
|
Definition
| a display to help assess whether a distribution of data is approximately Normal, if it is near straight, the data satisfy the Nearly Normal Condition |
|
|
