PAM Cheat sheet

# PAM Cheat sheet - A variable is a characteristic that...

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A variable is a characteristic that differs from one individual observation to next. Some, such as the color of a person’s eye, are categorical , and some, such as a family’s income, are quantitative . Cornell’s Ranking is neither – it is an ordinal variable We can organize these counts into a frequency table, which records the totals and the category names. Frequency tables and relative frequency tables describe the distribution of a categorical variable because they name the possible categories and tell how frequently each occurs. In a contingency table, the distribution of a variable by itself is called its marginal distribution . The distribution of a variable obtained by restricting the Who to consider only a smaller group of individuals is called a conditional distribution . Does the histogram have a single, central hump or several separated bumps? Humps in a histogram are called modes. A histogram with one main peak is dubbed unimodal; histograms with two peaks are bimodal; histograms with three or more peaks are called multimodal. Formula for the mean is : n y = = ns observatio of number Total the mean is the point at which a histogram of the data would balance. Think of the mean like the point at which a seesaw is at balance The range of the data is the difference between the maximum and minimum values Quartiles divide the data into four equal sections. The lower quartile is the median of the half of the data below the median; the upper quartile is the median of the half of the data above the median. The difference between the quartiles is the IQR, so IQR = upper quartile – lower quartile Five number summary: Minimum (min) First quartile (Q 1 ) Median Third Quartile (Q 3 ) Maximum Box plot: Central box spans the IQR. Line in the box marks the median. Lines extend from the box to mark min and max.

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## This note was uploaded on 04/03/2008 for the course PAM 2100 taught by Professor Abdus,s. during the Spring '08 term at Cornell.

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PAM Cheat sheet - A variable is a characteristic that...

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