Preparing a data table:
Not all that complicated !!!
By : The CEF professionals
2007
Photo : web
Photo : André Gagné
Photo : web
Why this presentation?
• To avoid the enormous waste of time often
associated with repeated but avoidable data
handling.
• To facilitate ready understanding of the data
set, even many years after it was first created!!!
?
Data sheets (1/2)
•
•
•
•
•
Write legibly.
Anticipate who might make use of the data.
Include the date.
Organise by line…
Anticipate any contentious cases & try to
work around these (% closing of forest cover
ou opening ?!)
Data sheets (2/2)
Localisation : chiffre site
Fiche placette centrale 400m²
Date:
Equipiers
Coordonnées
Peuplement
Azimut
Altitude
% fermeture au centre:
Exposition
Pente
Inventaire écoforestier:
Densité:
Pente:
Hauteur:
Exposition:
Perturbation:
Drainage:
Situation topo:
Type d'humus:
Prof. Humus:
Texture sol:
Type dépôt :
Prof. Dépôt:
Remarque :
Arbres sur pied (vivants ou morts)(dhp>9 cm)
No
DHP (2 État (9
Espèce
cm) classes)
No
DHP (2 État (9
Espèce
No
cm) classes)
État (9
DHP (2
Espèce
classes
cm)
)
The Data Table
Names of variables (1/5)
• Keep as simple & short as possible, but still
comprehensible!
• One variable = one column
• Several times for the same variable = several columns
• Break up complex categories: e.g., irrigated & fertilised
balsam fir in block 2
To break up the indicators: fir tree irrigated and fertilized in block 2
sujet
a
temps1
10.2
temps2
14.3
temps3
18.7
bloc espece
2 sab
fertilisation
irrigation
traitement
oui
oui
2-sab-fer-irr
The Data Table
Names of variables (2/5)
• Place class or categorical variables at the beginning
of the table, followed by the response variables.
• Whether using capital or small letters, be consistent,
as certain programs are case-sensitive (R)!!!
• Things to avoid :
– Special characters (/$%?&)
– Spaces
Be clear and precise, and include a comment sheet
where all abbreviations are explained
OR
If you are in Excel, use «Insertion / Comments»
Names of variables (3/5)
latérale
Names of variables (4/5)
• The «remarks» column in a data sheet =
imparts flexibility to a data table by allowing:
–inclusion in an analysis
or
–exclusion from an analysis
CHECK YOUR DATA
Names of variables (5/5)
The Golden Rule
One Line = One Sample
• Avoid the pain of having to start the process
all over, or having to make more or less
complex data manipulations.
Date
502
502
502
502
502
502
502
502
502
502
515
515
Point
1
1
1
1
1
1
1
1
1
1
2
2
Parcelle Echelle haut midh midb bas
A
10
50
40
20 70
B
10
0
0
10 10
C
10
0
0
10 10
D
10
40
50
40 50
I
25
0
70 100 100
J
25
0
0
25 70
K
25
95
90
90 60
L
50
50
60
70 50
M
50
60
50
80 70
N
50
95
85
95 100
A
10
20
50
40 100
B
10
0
5
15 75
Original data (1/6)
• Before all modifications, save a copy of the
original table & make modifications to a copy
that you can regularly save or back up.
Example: terrain2005ori.xls
terrain2005_05122006.xls
terrain2005_06122006.xls
etc.
Original data (2/6)
• In your Excel workbook, the sheet farthest to
the left should contain ONLY the original data in
a CONTINUOUS table
Date Point Parcelle Echelle haut midh midb bas
502
1A
10 50
40
20 70
502
1B
10
0
0
10 10
502
1C
10
0
0
10 10
502
1D
10 40
50
40 50
502
1I
25
0
70 100 100
Date Point Parcelle Echelle haut midh midb bas
502
1A
10 50
40
20 70
502
1B
10
0
0
10 10
502
1C
10
0
0
10 10
502
1D
10 40
50
40 50
502
1I
25
0
70 100 100
502
1J
25
0
0
25 70
Original data (3/6)
• NEVER leave cells empty
bloc couleur valeur
1 rouge
12
bloc couleur valeur
1 rouge
12
vert
bleu
2 rouge
18
44
15
1 vert
1 bleu
2 rouge
18
44
15
vert
bleu
16
14
2 vert
2 bleu
16
14
Original data (4/6)
• Missing data should be
indicated by « . »
• Careful, always differentiate
missing values from actual
zero (0) values!!!
bloc couleur valeur
1 rouge
12
1 vert
.
1
2
2
2
bleu
rouge
vert
bleu
44
0
16
14
Original data (5/6)
• Be consistent with your codes :
ABBA ≠ abba ≠ Abba
• Coding of numerical data with
« . » or « , » will depend on
what computer or operating
system you use?
If you aren’t sure…utilise the
decimal key in the calculator
section of the keyboard
bloc couleur valeur
1 Rouge
12
1
1
2
2
vert
bleu
rouge
vert
2 bleu
.
44
0
16
14
Original data (6/6)
• Include cases where species
Espèce
have not been observed
A
B
(NB in ecology!!!)
Site
Abondance
1
2
1
5
C
1
0
Espèce Site Abondance
A
2
4
A
1
2
B
2
0
B
1
5
C
2
3
A
2
4
A
3
0
C
2
3
B
3
5
B
3
5
C
3
0
C
4
2
A
4
0
B
4
0
C
4
2
Analysis of tables
• Move from left to right, ALWAYS keeping a
sheet that contains the raw data.
Une feuille pour les données
originales, les autres pour les
tableaux-croisés dynamiques ou les
graphiques
Dynamic graphics and Cross
tabulation
Data tables vs. Data bases
• A data table is organised by lines and by
columns.
• A data base is a collection of data sheets &
tables that allow you to store a great amount
of information.
Conclusion
•
•
•
•
Remain logical and structured.
Include raw data.
Save and back up, frequently.
«Comments» sheet (measurement units,
abbreviations, personnal notes …)
• REMEMBER:
The word «DATA» is plural!
The word «DATUM» is singular!
Questions?