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Preparing a data table: Not all that complicated !!! Photo : André Gagné Photo : web By : The CEF professionals 2007.

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Presentation on theme: "Preparing a data table: Not all that complicated !!! Photo : André Gagné Photo : web By : The CEF professionals 2007."— Presentation transcript:

1 Preparing a data table: Not all that complicated !!! Photo : André Gagné Photo : web By : The CEF professionals 2007

2 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!!! ?

3 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 ?!)

4 Data sheets (2/2) Remarque :

5 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 blocespecefertilisationirrigationtraitement 2saboui 2-sab-fer-irr sujettemps1temps2temps3 a10.214.318.7

6 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»

7 Names of variables (3/5)latérale

8 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

9 Names of variables (5/5)

10 Avoid the pain of having to start the process all over, or having to make more or less complex data manipulations. The Golden Rule One Line = One Sample

11 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.

12 Original data (2/6) In your Excel workbook, the sheet farthest to the left should contain ONLY the original data in a CONTINUOUS table

13 Original data (3/6) NEVER leave cells empty bloccouleurvaleur 1rouge12 vert18 bleu44 2rouge15 vert16 bleu14 bloccouleurvaleur 1rouge12 1vert18 1bleu44 2rouge15 2vert16 2bleu14

14 Original data (4/6) Missing data should be indicated by «. » Careful, always differentiate missing values from actual zero (0) values!!! bloccouleurvaleur 1rouge12 1vert. 1bleu44 2rouge0 2vert16 2bleu14

15 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 bloccouleurvaleur 1Rouge12 1vert. 1bleu44 2rouge0 2vert16 2bleu14

16 Original data (6/6) Include cases where species have not been observed (NB in ecology!!!) EspèceSiteAbondance A12 B15 A24 C23 B35 C42 EspèceSiteAbondance A12 B15 C10 A24 B20 C23 A30 B35 C30 A40 B40 C42

17 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.

18 Dynamic graphics and Cross tabulation

19 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.

20 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!

21 Questions?

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