preparing a data table: not all that complicated !!!
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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. - PowerPoint PPT PresentationTRANSCRIPT
Preparing a data table: Not all that complicated !!!
Photo : André Gagné
Photo : web
Photo : web
By : The CEF professionals
2007
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)Fiche placette centrale 400m²
Date: Equipiers
Coordonnées
Peuplement Azimut
Altitude
% fermeture au centre: Exposition
Pente
Inventaire écoforestier:Densité: Pente: Situation topo: Texture sol:Hauteur: Exposition: Type d'humus: Type dépôt :Perturbation: Drainage: Prof. Humus: Prof. Dépôt:
Arbres sur pied (vivants ou morts)(dhp>9 cm)
No EspèceDHP (2
cm)État (9
classes)No Espèce
DHP (2 cm)
État (9 classes)
No EspèceDHP (2
cm)
État (9 classes
)
Localisation : chiffre site
Remarque :
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
bloc espece fertilisation irrigation traitement
2 sab oui oui 2-sab-fer-irr
sujet temps1 temps2 temps3
a 10.2 14.3 18.7
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)
latéralelatérale
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)
• Avoid the pain of having to start the process all over, or having to make more or less complex data manipulations.
Date Point Parcelle Echelle haut midh midb bas502 1 A 10 50 40 20 70502 1 B 10 0 0 10 10502 1 C 10 0 0 10 10502 1 D 10 40 50 40 50502 1 I 25 0 70 100 100502 1 J 25 0 0 25 70502 1 K 25 95 90 90 60502 1 L 50 50 60 70 50502 1 M 50 60 50 80 70502 1 N 50 95 85 95 100515 2 A 10 20 50 40 100515 2 B 10 0 5 15 75515 2 C 10 20 40 10 20515 2 D 10 100 100 100 100515 2 I 25 20 30 75 100515 2 J 25 50 10 10 80515 2 K 25 20 80 100 100515 2 L 50 20 20 45 85515 2 M 50 5 30 30 85
The Golden Rule One Line = One Sample
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 bas502 1 A 10 50 40 20 70502 1 B 10 0 0 10 10502 1 C 10 0 0 10 10502 1 D 10 40 50 40 50502 1 I 25 0 70 100 100
Date Point Parcelle Echelle haut midh midb bas502 1 A 10 50 40 20 70502 1 B 10 0 0 10 10502 1 C 10 0 0 10 10502 1 D 10 40 50 40 50502 1 I 25 0 70 100 100502 1 J 25 0 0 25 70
Original data (3/6)
• NEVER leave cells empty
bloc couleur valeur
1 rouge 12
vert 18
bleu 44
2 rouge 15
vert 16
bleu 14
bloc couleur valeur
1 rouge 12
1 vert 18
1 bleu 44
2 rouge 15
2 vert 16
2 bleu 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 bleu 44
2 rouge 0
2 vert 16
2 bleu 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 vert .
1 bleu 44
2 rouge 0
2 vert 16
2 bleu 14
Original data (6/6)
• Include cases where species have not been observed
(NB in ecology!!!)
Espèce Site Abondance
A 1 2
B 1 5
A 2 4
C 2 3
B 3 5
C 4 2
Espèce Site Abondance
A 1 2
B 1 5
C 1 0
A 2 4
B 2 0
C 2 3
A 3 0
B 3 5
C 3 0
A 4 0
B 4 0
C 4 2
Analysis of tables
Une feuille pour les données originales, les autres pour les
tableaux-croisés dynamiques ou les graphiques
• Move from left to right, ALWAYS keeping a sheet that contains the raw data.
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?