In this module you will be addressing safety concerns as related to your project, performing your procedure and analyzing your data.
Safety:
The following forms will need to be filled out prior to experimentation
Safety Sheet-include in EVERY project
Humans as Test Subjects-include in projects involving surveys, learning, motivation, etc.
Microorganism Form-include in projects involving bacteria
Non-Human Vertebrate Endorsement-include in projects involving nonhuman vertebrates (ie mice, etc)
Tissue Culture Endorsement-include in projects involving cell lines/culturing
Experimentation:
Find an area in the lab in which your experiment will be performed.
Prepare by collecting ALL required equipment and materials. Put them in a cabinet and label the cabinet with your name. Please see me for name labels. Remember to think about clean-up. Do you need any special materials for disinfecting your work area, or for special disposal of materials or equipment.
Set up a schedule for experimentation. If you will need to use the lab during non-class periods, be certain that you have e-mailed the lab monitor(s) for the period(s) in which you will need supervision. Share your schedule with me before beginning your experimentation.
*Practice the protocol. Go through a dry-run using water in place of chemical, when possible.*
Prepare solutions, if possible. Find out if solutions can be stored or must be prepared immediately before experimentation.
REMEMBER to record all pertinent information in your lab journal.
Perform your experimentation.
Record the data, analyze your results.
Take pictures of set up, etc. to include in your final paper and on your board.
REFLECT, REFLECT, REFLECT!
Do you need to perform more trials? Do you need to redesign your protocol?
If necessary, redesign your experiment, set up a new schedule and share it with me. Remember, to use the advice and expertise of your mentor before, during, and after experimentation.
Analysis (make an appointment with Ms Taxakis to analyze your data geotax@d219.org)
Your data and observations are presented in this section, as well as the results of any analyses performed on those data and observations. Often data are presented in the form of tables and figures. This is appropriate only if the tables and figures are referred to in the text of the Results section, which should be written as a narrative in the past tense. Each table and figure should be constructed with a descriptive and properly placed caption. Please include at least one table that shows summary statistics for your data sets and at least one figure/graph that displays results, patterns or trends in your data (e.g., an X-Y scatterplot for a correlation analysis, or a bar or column graph that compares the means of multiple samples).
An Explanation of Different Statistical Tests
How to Choose a Test of Significance (from Mrs Taxakis)
This means your tables should have the following characteristics:
Information that is well organized into columns and rows
Variables that are properly labeled
Variables that contain metric units (if needed)
A complete caption/legend that …
Begins with a table number (e.g., Table 1. …)
Appears above the table
Describes what the table is showing
Provides any additional or missing information that is needed to fully understand the table
Your graphs should have the following characteristics:
Properly labeled axes with the first letter of the first word capitalized
Properly abbreviated metric units -- given in parentheses immediately after the label -- on the X-axis and/or Y-axis (if needed)
Axes with proper dimensions so that the data points fill the graph
Axes with properly spaced tick marks
The dependent variable on the Y-axis
A complete caption/legend that …
Begins with a figure number (e.g., Figure 1. …)
Appears below the graph
Describes what the graph is showing
Provides any additional or missing information that is needed to fully understand the graph
The first table to appear in a paper should be labeled as table 1, then next as table 2, and so on. Likewise, the first figure should be labeled as figure 1, the next as figure 2, and so on. It is strongly recommended that you look at several examples in scientific journals.
If you are using means (averages), then standard deviation and standard error (SE) should be calculated using Excel (Open Office).
Use this link to determine the appropriate statistical test.
Mean – the average of all data entries
Add up all entries and divide by the total # of entries
Use the Average function in Excel, highlight the cells you want to average and hit enter
Standard deviation (s) – the spread or dispersion in your data
Use the STDEV function (found in the statistical category in Excel), highlight the cells and hit enter.
Standard Error (SE) – the standard deviation of the mean
SE = s/square root of n, where s = standard deviation and n = sample size
In the cell where you want to calculate SE, click on the cell where standard deviation was calculated, then use the divide symbol (/) type in SQRT and enter the sample size in parentheses (sample size) – it should look something like this =C14/SQRT(10); C14 was the cell that contained the already calculated standard deviation, / means divide by, SQRT means take the square root of, and (10) was the sample size OR
The calculation might be entered as =STDEV(C2:C11)/SQRT(10); C2 though C11 are the cells that contain the data that you want to consider for calculation
You may then use the SE values for the + and – on your error bars
95% Confidence Interval (CI) - a 95% critical value of a student t-test distribution. This is a more accurate statistic for error bars.
95% CI = SE x t p(n-1)
Multiply the calculated SE value by the value of t at P= 0.05 (from a t-test table) for the appropriate degrees of freedom (df) for your sample (n-1)
If my sample size was 10, I would look at the t-test distribution table at 9 (10-1) under p = 0.05 and the value is 2.26. If my SE was calculated at 1.25 then the calculation would be =1.25*2.26
If 95% CI is calculated, then use these values as your + and – for the error bars.
Consult the LabWrite website for resources on graphing, calculating mean (averages), standard deviation, SE (standard error), and adding error bars to your graphs. Go to Using Error Bars in your Graph.
This link describes how to use Excel to calculate standard deviation, mean, and variance.
Here are some points to consider when writing your Results section:
Text is written as a narrative in the past tense.
Information is presented in an order or sequence that makes sense.
Tables and figures are cited in the text.
Tables and figures are complete with well-written captions. [Note: Figures should have properly labeled axes with units.]
Statistical results such as the test statistic (e.g., chi square value), degrees of freedom, and probability (e.g., P = 0.071) are given.
Writing is clear, concise, and free of grammatical errors.
Text is free of extraneous or trivial information.
Consult the Purdue Online Writing Lab (OWL) for resources on constructing figures and graphs.