Lab Report Explanation




Problem Statement
(Ask a Question)
When writing problems statements (which are sometimes included together with the background and hypothesis in an
introduction section of scientific study reports) one should follow the format below. This statement should summarize the
objective of the study and specifically mention the problem being addressed.
Describes the reason for performing experiment and what are the expected outcomes. This should provide the overall direction for
the laboratory investigation and must be re-addressed in the conclusion.
o “The effect of ____________ (Independent Variable) on ____________ (Dependent Variable)”
Background
(Observation)
After completing observations researchers should be able to include the following in the background/introduction part of their
reports:
1) Define the independent variable (what is manipulated) and justify how it will be manipulated
2) Define the dependent variable (what responds to the manipulation) and justify how it can be measured
3) Explain, with sufficient research evidence, the rationale for the expected relationship between the variables (reasoning or
basis for the hypothesis = Data-driven explanation for why the hypothesis is the answer for the research question). Make sure
to choose valid sources.
4) Explain how the independent variable should be changed and the reason for the expected change in the dependent variable
from successive change in the independent variable (how many levels of the independent variable, or different experimental
groups, should be tested and what each will do and why)
5) Note other things that could affect the dependent variable (other than independent variable) and why each should be kept
constant during the controlled experiment (how can other things affect the results if not controlled)
Hypothesis
(Propose an Answer to the Question)
When writing hypothesis (which are sometimes included together with problem statement and background in an introduction
section of scientific study reports) one should follow the following guidelines:
Note: It is possible to write an okay hypothesis without following a few of these guidelines, but a great hypothesis is the result
of following them all.
1) It should be stated directly. Without opening remarks such as “I think”, “I believe”. If necessary, introduce it as: “Researchers
hypothesize that….” Or “It is hypothesized that…”
2) It should be a complete, but concise statement (If is too long it is probably not very good)
3) It should establish a one-to-one relationship between variables (Easy with IF.. THEN… statements)
4) It should not introduce another factor that may affect the dependent variable. It should only include the relationship between 2
variables: one manipulated and one being tested (For example, Bad Hypothesis: If there is more wind and rain, then there will
be more erosion. In this example, there are 2 variables wind and rain, affecting erosion)
Note: There is an exception to this. In some advanced experiments, comparing the effects of multiple variables is actually
the point. In such experiments, researchers are actually doing multiple experiments in one. For example, one can increase
rain and see what happens to erosion. One can also increase wind and see what happens to erosion. One can also do both at
the same time and see what happens to erosion. Such experiments called factorial designs, do all of the above and then
analyze data from all three parts together to see the combined effect of 2 or more independent variables on the dependent
variable, as well as the relationship between the multiple independent variables. Such experiments either have multiple
hypothesis or complex hypotheses with multiple variables. For example: “If there is more wind, then rain will cause more
erosion.” & “If there is more wind, then thre is more erosion” & “If there is more rain, then there is more erosion”. Even
then, there is always a way to phrase a hypothesis as a relationship between two variables: “Rain erosion effects are
directly related to amount of wind”. When possible, this is preferred and is a mark of a good scientist.
5) Explanations for intermediate variables should be discussed in the background section or implied in the hypothesis (For
example, Bad hypothesis: Days are hotter than nights because the sun is hitting the unobstructed ground directly during the
day. A good hypothesis skips the sun as an intermediate variable and saves the explanation/rationale for the background
section. “Days are hotter than nights”. Alternatively, as mentioned in number 4, it is possible to work around this and find a
way to phrase the explanation for the phenomenon without introducing an additional variable: “Periods with direct
unobstructed ground sunlight exposure are hotter than periods without it.” But remember that hypothesis do need to be
considered as possible).
6) Variables are not defined in the hypothesis. All definitions and explanations for variables belong in the background (This is
related to item 5. A variable should not be explained within the hypothesis. For example: Bad Hypothesis: Days, or period
when the ground is directly exposed to the sun when not obstructed, are hotter than night, when the sun does not directly
shine on the unobstructed ground. Either state the summarize definitions as seen in 5, or just use the terms and remember to
be as consider as possible).
7) Hypothesis implies clear order of success for all levels of the independent variable (The order of success is clear even if more
than 2 groups are used in the design. For example, a study compares how the speed of an athlete depends on hours of training
and includes 3 groups: no training, 10 hour, and 20 hours of prior training. A bad hypothesis: “Athletes speed will be best
after 20 hours of training”. While this may be true, it does not address the differences between the 10 minute and control
group. A better hypothesis would be: “If training time increases, then athlete speed increases”. This serves as a predictor of
any possible group.
Note: Sometimes it is necessary to make multiple hypothesis for one experiment because one is testing several different
groups at once. For example, if one is testing how 3 different schools will perform in a test based on the programs they
institute, several hypothesis or a very complex one will be needed to describe the possible results: “Schools using program
A will earn higher scores than schools using program B.” & “Schools using program B will earn higher scores than schools
using program B” OR “Educational programs used will determine school scores in the following increasing order of
success: A, B, and C.” Of course, at times all one cares about is which one is the best so it does depend on the situaton. But
in general, it is often preferable to hypothesize about a general pattern than about what happens in a single situation.
8) It should be a testable and falsifiable statement (First, the hypothesis is not overtly obvious or impossible to falsify. There is a
chance that it can fail. For example, Bad Hypothesis: “Eating rice ultimately causes death”. Impossible to falsify since every
single person who ever ate rice has or will eventually die, unless humanity finds a way to stop death period. Second, a
testable statement means that the hypothesis implies the way the variables are manipulated and tested. For example, Bad
Hypothesis: “Bad kids are less intelligent”. This does not imply how one manipulates the character of the child, nor how
intelligence will be measured. A better hypothesis would be: “Kids who study less tend to perform worse in tests”. The
second hypothesis suggests a comparrison between children that study with different intensities and that success will be
measured through test scores. This is referred to operational definition of variables.


Testing
(Checking Your Proposed Answer)
Good designs obey the following criteria (applies to materials and procedure section):
1) Every single thing used is fully described to the extent that anyone replicating the experiment knows exactly what to use
2) List/drawing of all laboratory apparatus used in the investigation. Detailed enough to illustrate the configuration and with
measurements and variables to me measured included.
3) If a population is being studied, sample characteristics should be described (For example, in a study of college students the
following information should be included: number of people in each sample, how sample was acquired, and demographics
such as gender, ethnicity, country of origin, language, age, socio-economic status)
4) Procedures should be written in complete sentences in paragraph format, or given in an organized recipe-like, outline format.
5) Procedures should include every single step necessary for anyone replicating the experiment to do exactly what was done the
first time around. This includes:
 How the independent variable was manipulated (experimental process)
 How the dependent variable was measured (data collection process)
 The presence of experimental and control groups (control process)
 Efforts to maintain control or maintain constant, variables other than the independent could affect the dependent variable
(control process)
 Safety and ethical concerns
 Steps taken to maximize validity (reliability, precision, and accuracy), including:
o Sampling procedures (if applicable)
o Assortment procedures (if applicable)
o Repetition (if possible)
o Blinds or placebos (if applicable)
o Efforts taken to use better tools and methods
o Efforts taken to compare results with that of others for validity and generalization purposes
6) Data analysis procedure (Appears in the results/analysis section in most advanced scientific reports. But it is also important to
specify data analysis procedure including which statistical/quantitative analysis tests or qualitative methods were performed)
Analysis
(Understanding the Results)
When writing results/analysis sections of scientific study reports one should follow the following guidelines:
o Due to the importance of proper note-taking during the experiment, it is advisable to keep and submit notes all notes taken
during the lab. This should include quantitative and qualitative information, such as measurements and other observations
(errors, visuals, sounds, etc.)
o Results from notes sheet should be summarized clearly in complete verbal sentences
o If applicable, results section should include a descriptions of the procedures used to analyze data qualitative or quantitative
((This often includes a description of the test performed followed by a verbal description of the result in words and the scores
and confidence interval used in numbers. For example, results of a t test indicated a significant difference between the
groups, t = 5.64, a = 0.05)
o Results should also be displayed through the assistance of tables. Whenever possible, graphs should also be used. All tables
and graphs must be labeled (columns, rows, titles, axis, lines, etc) directly or through legends
o Units must be included for all measurements and results should include correct number of significant figures.
o Though results should be listed and statistically analyzed (if applicable), they should not be interpret in this session. That is
part of the conclusion

Conclusion
(Explaining the Results)
Good conclusions follow these criteria:
1) Should begin with conclusion analysis statement phrased like: “Results rejected / failed to reject the hypothesis that
_____________________ (restate hypothesis)
Note: Read about scientific laws later to understand why it MUST be phrased this way
2) This statement should be followed by an interpretation of the results that explains why the hypothesis was or was not
rejected.
3) If possible and applicable, comparisons with other similar investigations should be made
4) Then one should infer as to why the results turned out the way they did (especially if they rejected the hypothesis)
5) Limitations or errors during the experiment should be acknowledged (see above) and inferences should be made as to how
they affected the results
6) These errors and limitations should be addressed with suggestions on how to improve the study in future replications.
7) Real-life and/or science applications for results should be suggested, with notes as to how generalizable the experiment is
(The degree to which the control conditions of the experimetn match the real life conditions being studied is an important
factor in determining how and if the experiment should be applied in the field or in real life)
8) Conclusion should suggest future experiments or further research that could further explore the area or phenomenon
Communication
(Sharing & Peer Review)
In addition to lab reports (see Lab Report Template) scientist use presentations (see Science Fair Poster or Professional Poster
Templates) on website
To perform peer review critically analyze how well others follow this scientific method.