# Shared Flashcard Set

## Details

Biometry: Descriptive Statistics
Chapter 4
18
Biology
03/12/2013

Term
 Parameter
Definition
 The values in a population as a whole.
Term
 Statistics
Definition
 The values of a sample (n).
Term
 Central Tendency
Definition
 Several values can describe this, including; mode, median, mean, outliers, weighted mean, percentiles, and quartiles.
Term
 Mode
Definition
 Only measure of central tendency on a nominal scale, the most frequent item in the data set.
Term
 Median
Definition
 The value that has an equal number of items above and below it.
Term
 Mean
Definition
 The arithmetic average and is the most common measurement of central tendency when data are measured on an interval or ratio scale.
Term
 Outliers
Definition
 Rare observations in the tail of a distribution.
Term
 Weighted Mean
Definition
 Calculated from data arranged in a frequency distribution. x = Σfx/ΣfΣfx = sum of products (values of x and their frequencies) Σf = sample size (n)
Term
 Percentiles
Definition
 Divide up an array of data into 100 slices. So if you score in the 90th percentile 90/ of other people scored below you.
Term
 First Quartile (Q1)
Definition
 Divides the bottom quarter from the top three quarters and is the same as the 25th percentile.
Term
 Second Quartile (Q2)
Definition
 Also called the median (50th percentile), it divides the bottom two quarters from the top two quarters.
Term
 Third Quartile (Q3)
Definition
 Divides the top quarter from the bottom three quarters.
Term
 Dispersion
Definition
 The variation in observations around the mean (or median).
Term
 Range
Definition
 The difference between the largest and smallest items in the sample.
Term
 Interquartile Range
Definition
 The differences between the third and first quartiles and represents the spread of the middle 50% of the (ordered) values.
Term
 Box-Whisker Plot
Definition
 Used to illustrate the locations of the median, interquartile range, and range, and is often used to compare these characteristics in different groups.
Term
 Standard Deviation
Definition
 A measure of the average amount by which each observation is a series of observations differs from the mean.
Term
 Variance
Definition
 Represents the average of the squared deviations in the sample.
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