Data Selection and Retention - Case A1

Jocelyn Fox, a second-year graduate student, has just begun the experimental phase of her training program. She has initiated studies of novel agents on nitric oxide (NO) synthase, most recently in a controlled experiment involving a compound identified as SR582. In her first attempt at the experiment, Jocelyn made an error in dilution causing her inadvertently to test the compound at a concentration much higher than called for in the protocol. This yielded results quite different from those expected. She showed the data to her mentor , Professor Collins, who suggested in essence that she ignore the experiment because of the error. "In testing each compound, we always stop at a one nanomolar concentration," he said, "and have been able to compare stimulators and inhibitors quite well."

Jocelyn repeated the experiment, starting with the correct dilution, but then extended the experimental range all the way to a five nanomolar concentration (see Figure 1).

Figure 1.

This is Figure 1

Her plotted results were almost identical to the earlier curve obtained as a consequence of her dilution error and seemed to confirm the inhibitory effect she observed at greater than 1 nanomolar concentrations of SR582. Professor Collins was unimpressed when shown the data and suggested that she proceed to the next phase of the experimental plan now that she had mastered the technique.


  1. Have you obtained unexpected results that you could repeat? What were the consequences of the finding?
  2. If you were in Jocelyn's place, how would you respond to Professor Collins's inattention to her experimental findings?

Further questions:

  1. Assume that Jocelyn proceeded with the experimental plan, which consists of testing a group of novel compounds for their stimulatory and inhibitory actions on NO synthase at a O to 1 nanomolar concentration range. A month later, Jocelyn completed the work and was asked to write it up.

    How should she write up the standard experiment, given her doubts about the narrow range of the curve?

  2. In her continuing review of the literature on NO synthase, Jocelyn discovered a very recent paper indicating that NO—the product of the reaction—inhibits NO synthase when present in high concentrations in contained systems, such as the one with which she was working. When shown the paper, Professor Collins dismissed it and asked Jocelyn to write up the experimental results as she did them.

    What are Jocelyn's obligations in writing up the data? To herself, as first author? To her mentor? To her institution? To science itself? What should Professor Collins have told Jocelyn to clarify the situation?


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