|
Calculating
the Mean
Average Rubythroat First Arrival Dates
Step
1) Organize the data
List the dates of first sightings. In the "order" column, list
in which years hummers were seen first, second, and so on. If hummers
were seen on the same date in two different years, give them the same
order number.
First Spring Hummers in _____________________
|
| Date
of 1st Sighting
(by year) |
Order (1st, 2nd, etc) |
| f |
f |
| f |
f |
| f |
f |
| f |
f |
| f |
f |
| f |
f |
| f |
f |
| f |
f |
| f |
f |
| f |
f |
Step
2)
Determine
the range (the
difference between the earliest and latest dates in a set of data).
- The
earliest date is _____.
- The
latest date is _____.
- The
range is ____
days. (Number
of days from 1st to last sighting.)
Step
3)
Enter data on this second chart
- Write
in calendar dates, beginning with the earliest sighting (on line 1)
and ending with the latest one.
- Enter
all first sighting dates in the next column. When you have more than
one date that's the same, it goes on the same line.
-
In the last column, write in the values for each date entered. (If you
have 2 dates on that line, enter the value twice, and so on.)
- Add the
values for all the dates on your chart to get the total.
| Value
|
Calendar
Date |
Dates
of First Sighting
in state/hometown |
Values
for each date |
| 1
|
f |
f |
f
|
| 2
|
f |
f |
f |
| 3
|
f |
f |
f |
| 4
|
f |
f |
f |
| 5
|
f |
f |
f |
| 6
|
f |
f |
f |
| 7
|
f |
f |
f |
| 8
|
f |
f |
f
|
9 |
|
|
|
10 |
|
|
|
11 |
|
|
|
12 |
|
|
|
13 |
|
|
|
14 |
|
|
|
15 |
|
|
|
|
|
Total
|
f
|
Step
4) Calculate the Mean (the
average of all the values).
To determine the mean, take the sum (total) the values and divide by
the number of years. The answer will give you the order number of the
mean date.
(Total)
_____ divided by (# years) ____ = _____
So mean arrival date = _____
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