Writing a Lab Report• Why? To learn how to write a scientific publication

• Writing a factual report is an important skill in all walks of life

• Golden rule - Aim for Clarity

• Expect to have to write at least two drafts

• Use good English throughout, complete sentences, paragraphs etc.

• We can’t tell you exactly how to write a good lab report but we can give some general guidelines and some definite advice about what not to do.

• Look at Journals in the library/on the web– Physical Review Letters, American Journal of Physics

Mechanics

• First report at end of 4 week standard experiment

• Assignment of a report title – discussion with demonstrator

• Can get full marks for a report even if the experiment was incomplete or even a failure.

• You get approx. 1 week to complete report

• Report marked by demonstrator, second marked by HoE, returned to you by demonstrator, discussion.

• Late reports – See Handout for rules!

Style

• Impersonal, avoid first person - I/we

• Best to use passive voice – “The function generator was connected to the oscilloscope using a coaxial cable” rather than “I connected the function generator to the …”

• For exceptions to this rule see handout

• How long should the report be? 4-6 sides of A4 including graphs and figures. Any extra material can go in an appendix. e.g. program listing, long calculations etc.

Structure

• Title• Abstract• Introduction• Theory• Method• Results, Discussion, Errors• Conclusion• Bibliography• Appendices

– See handout for alternative structures

Abstract• To know how to write one you need to know what they are for!

• People browse abstracts to decide whether they are interested enough to warrant actually reading the paper/visiting the poster/attending the talk

• They are a brief synopsis of what has been done and what method was used. Any key results (and their associated errors) should be quoted and main conclusions should be stated.

• Example:– We report an experimental determination of the wavelength of light emitted by a

commercial diode laser used in a compact disc player. The measurement was made using a commercial spectrometer employing a diffraction grating with 1800 lines/mm. The wavelength was found to be dependent on the current in the diode and was measured to be (781.3 0.2)nm at the recommended operating current of 100mA.

Introduction• Give background to what you are doing and why

• Introduce the ideas you will need later in the report without going into detail

• Put your experiment in context.

Theory• Use prose and equations. Here and elsewhere an important

rule is – Always start a new section with a sentence i.e. not with an equation, table, figure etc..

• Punctuate equations, for example:

Force F is defined by

F = ma,

where m is the inertial mass and a the acceleration.

Method• Say what you did and why.• Use passive voice

“The pendulum was displaced from the equilibrium position by 2 cm and tied in place with a piece of cotton.”

• Never use the kind of ‘cook book’ style adopted in many lab scripts. i.e. don’t use the imperative (i.e. don’t instruct the reader what to do). “Connect the photodiode to the oscilloscope and make a note of the voltage” is not appropriate for a laboratory report.

• Don’t give list of apparatus. Describe each piece of apparatus when it comes up in the description of the work.

Results, Errors, Discussion

• Describe your results

• Discuss the sources of error

• Analyse the effect these errors have on your results

• Discuss what your results mean i.e. draw conclusions from your results

• Three constructs – text, tables, figures

• If it isn’t text or a table it is a figure, including graphs, drawings, charts, plots…

• All figures should have a figure number and a caption and you should refer to the figure by number not like “as can be seen in the figure below”

Tables

• If you have a graph, you don’t need a table! (save the numbers for your lab book)

• If you want to include a table, don’t! Think about how you could present the results as a graph instead.

• For ideas, see E. R. Tufte, Envisioning Information.

Conclusions

• Briefly restate the aims of the experiment and method used

• Draw all the elements of the report together

• Point out successes and failures

• Say what you have achieved and learned (use the passive voice here)

• Say how the experiment could be improved.

• Avoid making subjective or personal statements like “…the experiment was a great success and I learned how to use an oscilloscope….”. The ending can be rather abrupt.

Bibliography

• Essential to include one – See handout

Appendices

• Extra material, included for completeness

• Do not put your results here i.e. graphs or tables

Common Mistakes

• Don’t rewrite the lab script

• Don’t use default Excel “style” for graphs

• Write meaningful figure captions

• Reread! Computers catch spelling mistakes, but they can’t flag nonsense!

Summary

• Strive for clarity – Use correct, plain English – Avoid the use of

• Write a first draft

• Read the handout – The markers have!

• Write a final draft

• If your word-processor/drawing package doesn’t do what you need, do it the old fashioned way, pen and paper.