Data collection
Guidelines for collecting and
checking data
Type of data
z Quantitative
- Height, diameter, density
z Qualitative
- Stem straightness
Choosing traits
for measurement and
assessment
• survival
• dbh
• height
• stem volume
• wood density, colour
• timber strength, stiffness
• timber defects
• pulp yield
• fibre length
• stem straightness
• axis persistence/forking
• branch thickness
• branch angle
• pest and disease resistance
• growth stress
• tension wood
• fodder production
• fodder value
• other traits?
?

2 = flowering
z Subjective - e.g. stem straightness
1 = worst 2% of trees in trial
2 = next best 15% of trees in trial
3 = next best 33% of trees in trial
4 = next best 33% of trees in trial
5 = next best 15 % of trees in trial
6 = best 2 % of trees in trial
Assessing stem straightness - subjective
scoring system
worst
Prior to scoring,
inspect trial and set
proportions of scoring
categories to
approximate normal
distribution - improves
heritability of trait
Stem straightness
1
2
43
5
6
best
33%
2%
15%
Frequency
Assessing traits

Forking defined as two or more leaders, stem diameter of smaller leader
is more than 50% of diameter of larger leader just above fork
Data collection
z Indexing information on the field data sheets
z Data sheets should be prepared with layout and
treatment information included: replicate number,
plot number, tree number, seedlot number, etc.
Indexing in field order - RCB design
Repl Plot Tree Seedlot ht03 ht04 dbh04
1 1 1 4 2.7
1 1 2 4 0.8
. . . .
. . . .
2 5 7 2
*
2 5 8 2 3.2
Collect data in field order
• Indexing information should be in field order,
NOT treatment order
• Measure a replicate at a time, using same
team, to avoid bias
• Successive measures should be in the same
order
Col 1
2
3 4 5 6 7 8 9 10 11 12
Rep 1
1

1412442355747453610 5

30 m
12 columns x 5 trees x 1.5 m = 90 m
z 60 families
z 5 tree row plots
z 5 replicates
z 5 rows and 12 columns
z spacing 3m between
rows
z spacing 1.5m between
trees within rows
z each seedlot occurs
only once in any long
column
Latinised row column design for seedling seed orchard with 60 families
Assess the trial
in field order !!!
One line - one tree!
z One line on the data sheet should be
used for each experimental unit (usually
a tree).
z Measurements such as height and
diameter are put in columns across the
data sheet after the indexing columns.
Data sheet
repl plot tree seedlot height dbh
1 1 1 4
1 1 2 4
1 1 3 4
1 1 4 4
1 1 5 4

screen, with somebody checking the field
data sheet against the values which are being
read out
General tips for computer analysis of data
z Keep all the files for an experiment in one folder (directory)
z Check to see whether you are operating in the right working
folder/directory
z Keep a back-up copy of important files such as your original data
file
z As you will most likely modify the original data file, work with a
copy under a different name e.g. benthamii2.xls
z Save your work frequently so it is not lost in a power failure, or if a
program crashes
Excel tips
z Edit\Goto\special\blanks - locate blank cells
in the block of data you have entered
z =max(F2:F4000) - identify max. value in range
F2:F4000
z =min(F2:F4000) - identify minimum value
z =average(F2:F4000) calculate mean
Data should make biological
sense! Are these trees OK?
height diameter at diameter at
ground level breast height
tree (m) (cm) (cm)
1 15.5 19.5 15.6
2 1.1 3.5 0
3 15.6 14.5 22.8
4 * * 13.0
5 1.1 4.2 2.1