Term project
Statistics 100A, Fall 2015
Interim report due November 2, 2015
Final report due December 4, 2015
The data set tree failure contains information on failures in Quercus – lobata also called
Valley oak.
The data set contains the following variables:
failtype: type of failure (branch, trunk or root failure)
variables related to trunk failure:
tfailheight : height of trunk at which failure occurred
tbreakdia: diameter of the trunk at which failure occurred
fportiondead: whether or not the failed portion of the tree is dead (y/n for yes/no)
decay: whether or not there is decay (y/n)
lean: whether or not the tree has an uncorrected lean (y/n)
cracks: whether or not there are cracks in the trunk (y/n)
mechanical: whether or not there is mechanical injury to the trunk (y/n)
animal: whether or not there is animal injury to the trunk (y/n)
insect: whether or not there is insect injury to the trunk (y/n)
variables related to branch failure:
cleaned: whether or not the canopy has been cleaned (y/n)
thinning: whether or not there has been thining of branches (y/n)
variables related to root failure:
moisture: the moisture condition of the root at the time of failure
irrigation: irrigation of the tree
general variables related to the trees
age: age of tree
height: height of tree
dbh: diameter of tree at base height
windspeed: wind speed at time of failure
temperature: temperature at time of failure
precipitation: precipitation at time of failure
cleanup: cost of the clean up after failure
Interim report: provide a description of all variables; if the variable is continuous you
should obtain mean and standard deviation and five number summaries. For qualitative
variables you should provide frequency tables. The interim report should be about 2
pages, single spaced or 1.5 line spacing. Do not use double spacing. The report is due
on November 2. No late report will be accepted.
Final project: it is due on December 4, no late projects accepted. Answer the following
questions:
• Is there an association between age, height or dhb and type of failure?
• Does wind speed make any difference in the type of failure?
• Does precipitation make any difference in the type of failure?
• Is temperature related to type of failure?
• Which type of failure had the costliest clean up?
• Describe moisture conditions at time of root failure. Did more trees experience
root failure when it was dry or after rain, when the ground was wet?
• For branch failures was it more or less likely that the tree had been thinned or
cleaned?
• Provide information on the height and diameter at which the trunk failure
occurred in the trees that experienced a trunk failure.
• Did a majority of trees have mechanical, insect or animal injury that experienced
a trunk failure?
• What other conditions were notable in the trunk failures such as cracks, lean or
decay? What about the crown, was it dense?
• For trunk failures is there an association between decay and whether or the
failed portion is dead?
• For branch failure is there an association between cleaned and thinning?
• For root failures, is there an association between the moisture condition and
precipitation?
You can answer these questions in the order you wish but it should be coherent. Your
final report should not exceed 5 pages, not counting graphs and other materials that you
may add as an appendix. Major graphs and tables should be in the report, however,
there should not be more than 2 or 3 tables at most and graphs should be included if
they serve to make a point. The report should contain the following sections:
a. Summary – a brief overview
b. Introduction – motivation of the analysis
c. Methods – the statistical methods used
d. Results – your findings, this is the main part of the report
e. Conclusion
f. Appendix as needed
You can work in groups of up to three people or you can work alone. If you work as a
group, you will submit only one report. The groups have to be determined by the time of
the interim report. There will be no exception to the limit of three people per project and
no changes after November 2.

Term project
Statistics 100A, Fall 2015
Interim report due November 2, 2015
Final report due December 4, 2015
The data set tree failure contains information on failures in Quercus – lobata also called
Valley oak.
The data set contains the following variables:
failtype: type of failure (branch, trunk or root failure)
variables related to trunk failure:
tfailheight : height of trunk at which failure occurred
tbreakdia: diameter of the trunk at which failure occurred
fportiondead: whether or not the failed portion of the tree is dead (y/n for yes/no)
decay: whether or not there is decay (y/n)
lean: whether or not the tree has an uncorrected lean (y/n)
cracks: whether or not there are cracks in the trunk (y/n)
mechanical: whether or not there is mechanical injury to the trunk (y/n)
animal: whether or not there is animal injury to the trunk (y/n)
insect: whether or not there is insect injury to the trunk (y/n)
variables related to branch failure:
cleaned: whether or not the canopy has been cleaned (y/n)
thinning: whether or not there has been thining of branches (y/n)
variables related to root failure:
moisture: the moisture condition of the root at the time of failure
irrigation: irrigation of the tree
general variables related to the trees
age: age of tree
height: height of tree
dbh: diameter of tree at base height
windspeed: wind speed at time of failure
temperature: temperature at time of failure
precipitation: precipitation at time of failure
cleanup: cost of the clean up after failure
Interim report: provide a description of all variables; if the variable is continuous you
should obtain mean and standard deviation and five number summaries. For qualitative
variables you should provide frequency tables. The interim report should be about 2
pages, single spaced or 1.5 line spacing. Do not use double spacing. The report is due
on November 2. No late report will be accepted.
Final project: it is due on December 4, no late projects accepted. Answer the following
questions:
• Is there an association between age, height or dhb and type of failure?
• Does wind speed make any difference in the type of failure?
• Does precipitation make any difference in the type of failure?
• Is temperature related to type of failure?
• Which type of failure had the costliest clean up?
• Describe moisture conditions at time of root failure. Did more trees experience
root failure when it was dry or after rain, when the ground was wet?
• For branch failures was it more or less likely that the tree had been thinned or
cleaned?
• Provide information on the height and diameter at which the trunk failure
occurred in the trees that experienced a trunk failure.
• Did a majority of trees have mechanical, insect or animal injury that experienced
a trunk failure?
• What other conditions were notable in the trunk failures such as cracks, lean or
decay? What about the crown, was it dense?
• For trunk failures is there an association between decay and whether or the
failed portion is dead?
• For branch failure is there an association between cleaned and thinning?
• For root failures, is there an association between the moisture condition and
precipitation?
You can answer these questions in the order you wish but it should be coherent. Your
final report should not exceed 5 pages, not counting graphs and other materials that you
may add as an appendix. Major graphs and tables should be in the report, however,
there should not be more than 2 or 3 tables at most and graphs should be included if
they serve to make a point. The report should contain the following sections:
a. Summary – a brief overview
b. Introduction – motivation of the analysis
c. Methods – the statistical methods used
d. Results – your findings, this is the main part of the report
e. Conclusion
f. Appendix as needed
You can work in groups of up to three people or you can work alone. If you work as a
group, you will submit only one report. The groups have to be determined by the time of
the interim report. There will be no exception to the limit of three people per project and
no changes after November 2.