Upload
melvin-burns
View
215
Download
0
Embed Size (px)
Citation preview
GraphsGraphsDisplaying Data
GraphingGraphing Graphs are visual displays of data. Different types of graphs are used for
different purposes. The correct type of graph must be used for
the data collected. In other words, the data determines the graph
type…you don’t choose the type you want!
Discrete or Continuous?Discrete or Continuous? When deciding on the type of graph to make, ask
yourself: Is my independent variable discrete or continuous?
Discrete variables are categorical e.g.: gender, brand of fertilizer, type of sandwich Use a BAR GRAPH with these variables
Continuous variables are associated with measurements involving a standard scale with equal intervals e.g. amount of fertilizer in grams, time in seconds Use a LINE GRAPH with these variables
Graph TypesGraph Types Line graph
Shows relationship between two variables Used to help show the trend, or pattern, in data Trends allow for predictions Independent variable goes on horizontal axis (x) Dependent variable goes on vertical axis (y)
Bar graphs Display data that is not continuous Used to show comparisons between different sets of data or
categories Pie Chart
Uses circle sections to show parts of a whole
Making a Line GraphMaking a Line Graph Will be used in most of our experiments Must have title, labeled axes, & units Must have reasonable spacing Line must take up graph space
Line shouldn’t be to right or left of graph space Line shouldn’t be to top or bottom of graph space Line should be fairly centered, so make axis numbers fit your
data Line should extend through (0,0) point when appropriate Line should NOT extend through (0,0) point when NOT
appropriate
Line Graph ExampleLine Graph Example What is this a graph
of?
How do you know?
N.Y. Temperatures
Title
Line Graph from DataLine Graph from Data
Time is continuous. There are other time measurements possible between the measurements recorded. The experimenter could have recorded the temperature every hour, every half hour, or every minute. Therefore, a line graph is appropriate.
Best-Fit Line Graph best fit line graph
– see p. 18 Connects with
best smooth & continuous line
Doesn’t necessarily go through all data points
gets average.
Best-Fit Line GraphAll show trend All allow for prediction
Straight-line fit Smooth curve fit Smooth curve fit
Bar GraphBar Graph
A Bar Graph is appropriate here because the data shows lunch choices. Each choice is a separate category
Bar GraphBar Graph
Categories are the horizontal axis.
Measurements are on the vertical axis.
Each category has a separate bar.
Pie Chart Pie Chart (Circle Graph)(Circle Graph)
A Pie Chart would be appropriate here to see what percent of students choose each type of exercise
Pie Chart Pie Chart (Circle Graph)(Circle Graph)
1 student of 8 chose swimming: 1/8 = .125 (x 100 = 12.5%) (1/8 of the circle)
2 students out of 8 chose jogging: 2/8 x 100 = 25% (1/4 of the circle)
4 students out of 8 chose soccer: 4/8 x 100 = 50% (1/2 of the circle)
Slope of a LineSlope of a Line Slope is determined
using the formula:
Two points are selected on the line. The coordinates of those points are taken.
Two points: (2, 3) and (4, 9)
point 1 coordinates and point 2 coordinates
so:
(2, 3) and (4, 9) 9-3 = 6 = 3 4-2 2
The slope of this line is 3.
X1, Y1 X2, Y2
Slope of a LineSlope of a Line What is the slope of
this line? Let’s call R point 1 and
S point two. R coordinates: (1, 6)
S coordinates: (4, 12)
Slope =
X1, Y1
X2, Y2
12 - 6 = 6 = 2 4 - 1 3