Transcript Statistics for Research in Ecology

Natasha Viener
Sharks
Average Length of Sharp Nosed Sharks
1000
L
e
n
g
t
h
o
f
S
h
a
r
k
s
(
c
m
990
980
970
960
950
940
)
930
MALES
FEMALES
Gender of Sharks
Turtles
Survival of the Sea Turtles
N
u
m
b
e
r
o
f
25
20
15
10
T
u
r
t
l
e
s
5
0
started out
blue
yellow
green
Colors
survived
red
orange
Bottle Caps
Percent of Total Number of Caps
red
orange
yellow
blue
green
purple
black
white
clear
other
Sea Cigars
Length of Sea Cigars
N 12
u
m
b 10
e
r
o
f
S
e
a
8
6
4
C
i
g
a
r
s
2
0
Size Interval
(cm)
"1-5"
"6-10"
"11-15"
Size (cm)
"16-20"
"21-25"
"26-30"
Corals
Probability - The chance that something will occur in relation to
the possible alternatives
Many things can affect the coral and harm them
• Water temperature must be warm between
70 - 80° F or 21 - 29 ° C
• Sunlight so the algae can function
• Clear water to let sunlight through
• Clean water because they are sensitive to pollution
• Saltwater because they need a certain salt to water ratio
Variance
•
Variance - Two values that are used in
statistics to describe how far away your data
are from the mean
TDC ( theoretical distribution curve)
of Sea Cigars
Theoretical Distribution Curve – The ideal picture of a
distribution based upon random sampling
3
TDC of 25 Mangrove Seedlings
2.5
F
2
r
e
q
u 1.5
e
n
c
1
y
0.5
0
0
5
10
15
Length (cm)
20
25
TTest
TTest – an equation used to calculate the
t-statistic designed to test whether there is a
significant difference between the means of
two independent samples. This equation
includes the mean, the number, the variance
and the probability.
Chi-Square
A Chi-square test is used to see if there are any
significant difference between data sites or
sources. Since p < .05 we reject the null
hypothesis and therefore there is a significant
difference in the survival rates between beach
sites.
Butterflies
Control Group
Total
Treatment
Group
Total
C1
16
T1
20
C2
20
T2
20
C3
20
T3
20
C4
20
T4
21
C5
20
T5
20
C6
Dead
T6
Dead
C7
Dead
T7
20
C8
20
T8
20
C9
20
T9
20
C10
Dead
T10
Dead
C11
20
T11
N/A
C12
20
T12
20
C13
20
T13
Dead
C14
20
T14
20
C15
20
T15
20