Transcript Statistics for Research in Ecology

STATISTICS FOR
RESEARCH IN ECOLOGY
By: Alexander Rodriguez
SHARKS
Average legnth of Atlantic Sharpnose Sharks
1000
990
Legnth (cm)
980
970
960
950
940
930
920
Male
Female
Gender Of Sharks
SEA TURTLES
The Survival Rate of Sea Turtle Hatchlings
25
Number of Sea Turtles
20
15
10
5
Started Out
0
green
Survived
red
Color of Sea Turtle
orange
MARINE DEBRIS
other
4%
Percentage of Bottle Cap Colors
orange
1%
yellow
3%
red
14%
clear
31%
blue
14%
white
16%
black
8%
green
9%
purple
0%
FREQUENCY OF SEA CIGAR
LENGTHS
Number of sea cigars
12
Frequency
10
8
"1-5"
"6-10"
6
"11-15"
"16-20"
"21-25"
4
"26-30"
2
0
"1-5"
"6-10"
"11-15"
"16-20"
Length in Centimeters
"21-25"
"26-30"
CORAL PLANULA
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Probability- A way to measure the chances of something
will occur in relation to the possible alternatives.
Things that can kill coral
Shallow depth in water (less than 150 ft)
Water temperature if it’s to cold (16-30°C or 61-76°F)
Boats go right over them and destroy them
Chemicals that get on them kill them
Wave action if it is very weak
Some don’t get enough sunlight so they die
Boat anchors crash them when they get thrown down
VARIANCE AND STANDARD
DEVIATIONS
Variance- The fact or quality of being different,
divergent, or inconsistent. The formula is O².
 Standard Deviation- How spread out the data
are. The formula is O.
 Example: If there are some dogs short or tall it
would be a difference because the Rottweiler
would be the biggest dog while all the other dogs
like the terriers or dachshunds would be a lot
shorter causing a difference in the mean.
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T.D.C.
Theoretical Distribution of 25 sea cigars
3
2.5
Frequency
2
1.5
1
0.5
0
0
5
10
15
20
Legnth of sea cigar

Theoretical Distribution curve(bell)- A theoretical or ideal picture
of a distribution based upon random spelling.
25
T-TEST
T-test: An equation you will use to calculate the
t-statistics which is a test designed to tell the
significance between the two independent
samples.
 In the t-test it needs the mean, the number, and
the variance.
 If the t-test is higher than the p-value then you
have to reject the null hypothesis.
 In our case we had to because there was a
significant difference.
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CHI-SQUARE
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A chi-square test is a statistical test commonly
used for testing independence and goodness of fit.
We played a sea turtle game to see how many
turtles out of 100 will survive in the different
beach sites. There were 500 turtle at first but by
the end of the game 229 were left alive and 271
turtles died.
We finally rejected our null hypothesis, and
accepted our alternative hypothesis because
there was a significant difference in the survival
rate at the different beach sites.