proper graphical presentation of data makes it easier to understand what's going on with the data and may suggest some types of analysis

computers have made the creation of graphs and tables easier but you need to understand how they are constructed

in a cultural sense it is the notion that people tend to minimize travel distance for most trips

research has repeatedly shown that in aggregate as distance increases the number of trips falls

such a phenomena can be displayed as a graph in 2 dimensions (Y and X)

the Y axis is typically the dependent variable and X is the independent variable

the first and most elementary step in measurement is to define what characteristics we are interested in

once we've done that we want to know as much as possible about it

graphs can help here

a very common graph is the histogram, which shows a frequency distribution

it is a vertical or horizontal bar chart on which each bar represents a certain value range of the distribution and the length of the bar shows the frequency of values in that value range

its purpose is to show how the values are distributed between the min and max values

the range with each class should be uniform with the possible exception of the extreme ones

another alternative is the frequency polygon

it just a line chart connecting the frequency values

maps have 4 major advantages

1) they present a simultaneous representation of all of the data

2) they contain the 'spatial structure'

3) maps are models

4) they are communication devices

types

1) dot maps

2) network maps

3) contour maps

4) choropleth maps