1. Graphs Each point represents one row in a table.
A graph is a line plot of a data set.
Each point represents one row in a table.

2. Table and Graph Sam's Weight Month Weight in kg January 49 February 54
March 61
April 69
May 73

3. A graph must include: Title with both variables Even scale
Labeled axes with units
Correctly plotted data
Correctly placed variables on axes
Key, if applicable
Must be neat, easy to visualize trend

4. DATA
Data is the core of scientific investigation. Scientists look for trends in data and then try to explain the trend.
Scientists use graphs to see the trend in the data.

5. TREND
The connecting lines allow us to visualize the TREND in the data.
You should be able to look at a graph and summarize the trend shown by the graph.

6. Placement of variables
Dependent variable:
Y axis
Independent variable:
X axis

7. REMEMBER!!!!
IndeX
Independent in the X (axis)

8. How to determine the variables?
The DEPENDENT depends on the
INDEPENDENT
The _________ depends on the
________.

9. Title
The title must include both variables and the scientific name of the organism:
Example: “ The effect of Miracle Grow on the growth of Phaseolus vulgaris”

10. Number of survivors (log scale)
Title?
1,000
100
Number of survivors (log scale)
Females 10
Males 1 2 4 6 8 10
Age (years)

11. Line Graph
It is used when there is a sequence though time from one point to another, or when you are measuring a variable that changes with distance from a fixed point.
It allows you to see increasing or decreasing trends

12. LINE GRAPHS REMEMBER!!! IN BIOLOGY, YOU WILL USE MOST OF THE TIME.
(No bar graphs unless instructed to.)

13. Identify the elements in this graph
Value of Sarah's Car
Year
Value
2001
$24,000
2002
$22,500
2003
$19,700
2004
$17,500
2005
$14,500
2006
$10,000
2007
$ 5,800

14. 1.IMPROVE the title of this line graph.   
2.What is the range of values on the horizontal scale?
3.What is the range of values on the vertical scale?
4.How many points are in the graph? 
5.What was the highest value recorded?
6.What was the lowest value recorded?
7.Did the value of the car increase or decrease over time? (trend)

15. QUESTION
ANSWER 1.
Improve the title of this line graph?   
Value of Sarah's Car from ‘01 to ‘07 2.
What is the range of values on the horizontal scale?
2001 to 2007 3.
What is the range of values on the vertical scale?
0 to 25,000 4.
How many points are in the graph?    7 5.
What was the highest value recorded?
$24,000 6.
What was the lowest value recorded?
$5,800 7.
Did the value of the car increase or decrease over time?
decrease

16. Does feeding by sea urchins and limpets affect seaweed distribution
Does feeding by sea urchins and limpets affect seaweed distribution? Experiment by WJ Fletcher near Sydney, Australia
Sea
urchin 80
Both limpets
and urchins
removed 60
Seaweed cover (%)
Only
urchins
removed
Limpet 40
Only limpets removed 20
Control (both
urchins and
limpets present)
August
1982
February
1983
August
1983
February
1984

17. SCATTER POINT GRAPH
It is used when there is no reason to assume any sequence between points. It has no line connecting the points – each point represents an independent, random event.
It allows you to see broad increasing or decreasing trends in the data.

18. Average number of seeds per reproducing individual
4.0
10,000
3.8
3.6
Average number of seeds
per reproducing individual
(log scale)
1,000
Average clutch size
3.4
3.2
3.0
100
2.8 1 10
100 10 20 30 40 50 60 70 80
Plants per m2 (log scale)
Females per unit area
Plantain. The number of seeds produced by plantain (Plantago major) decreases as density increases.
Song sparrow. Clutch size in the song sparrow on Mandarte Island, British Columbia, decreases as density increases and food is in short supply.

19. Number of Paramecium/mL
1,000
800
600
Number of Paramecium/mL
400
200 5 10 15
Time (days)
A Paramecium population in the lab

20. Bar Graph
It is used when the independent variable represents a category rather than a numerical value. Only the height of the bar has any numerical meaning.
It allows you to see differences between the categories or groups of categories.

21. Parents surviving the following winter (%)
100
Male
Female 80 60
Parents surviving the following winter (%) 40 20
Reduced
brood size
Normal
brood size
Enlarged
brood size

22. Pie Graph
A pie chart (or a circle graph) is a circular chart divided into sectors, illustrating relative magnitudes or frequencies or percents. In a pie chart, the arc length of each sector, is proportional to the quantity it represents. Together, the sectors create a full disk. It is named for its resemblance to a pie which has been sliced.
While the pie chart is perhaps the most ubiquitous statistical chart in the business world and the mass media, it is rarely used in scientific or technical publications

23. How to establish a relationship from a graph
The relationship is
linear if you can draw a straight line through the data points
Inverse if the graph of the relationship appears to be a curve.
Inversely proportional to x. As x increases, y decreases
there might be no relationship at all. In this case, you may see data points scattered in an irregular cloud so that you cannot draw a straight line or a smooth curve through them.

24. What can you tell about this graph?

25. 180
150
120
Number of Daphnia/50 mL 90 60 30 20 40 60 80
100
120
140
160
Time (days)
A Daphnia population in the lab

26. Number of females 1975 1980 1985 1990 1995 2000 Time (years)60
Number of females 40 20
1975
1980
1985
1990
1995
2000
Time (years)
A song sparrow population in its natural habitat

27. Infant mortality (deaths per 1,000 births) Life expectancy (years)60 80 50 60 40
Infant mortality (deaths per 1,000 births)
Life expectancy (years) 30 40 20 20 10
Developed
countries
Developing
countries
Developed
countries
Developing
countries

28. Ecological footprint (ha per person) Available ecological capacity16 14 12
New Zealand 10
USA
Germany
Ecological footprint (ha per person) 8
Australia
Netherlands
Japan
Canada
Norway 6
Sweden UK 4
Spain
World 2
China
India 2 4 6 8 10 12 14 16
Available ecological capacity
(ha per person)

29. They can illuminate social conditions and help us plan for the future
Age structure diagrams can predict a population’s growth trends
Rapid growth
Afghanistan
Slow growth
United States
Decrease
Italy
Male
Female
Age
Male
Female
Age
Male
Female
85+
80–84
75–79
70–74
65–69
60–64
55–59
50–54
85+
80–84
75–79
70–74
65–69
60–64
55–59
50–54
45–49
40–44
35–39
30–34
25–29
20–24
15–19
10–14
5–9
0–4
45–49
40–44
35–39
30–34
25–29
20–24
15–19
10–14
5–9
0–4 8 6 4 2 2 4 6 8 8 6 4 2 2 4 6 8 8 6 4 2 2 4 6 8
Percent of population
Percent of population
Percent of population
They can illuminate social conditions and help us plan for the future

30. Human population (billions)
The human population increased relatively slowly until about 1650 and then began to grow exponentially 6 5 4
Human population (billions) 3 2
The Plague 1
8000
B.C.
4000
B.C.
3000
B.C.
2000
B.C.
1000
B.C.
1000
A.D.
2000
A.D.

31. Birth or death rate per 1,000 people
The demographic transition is associated with various factors in developed and developing countries 40 30 20
Birth or death rate per 1,000 people 10
Sweden
Mexico
Birth rate
Birth rate
Death rate
Death rate
2050
1750
1800
1850
1900
1950
2000
Year