Answer:
She needs to change the manipulation of her study by changing the measurements, possibly.
Step-by-step explanation:
The Null Effect is a result, in science experiments that do not produce the desired or proposed result. Such experiments do not help to support the hypothesis. The word 'null' means 'nothing' or 'empty' thus the results in an experiment that does not give the desired results as proposed are term as 'null results or effects.'
In the given case, the null effect of Dove's experiment is because of the improper measurement of the variable. She can troubleshoot her experiment by changing the measurements of her variable, which is chocolate. It is because an ounce of chocolate equals to no chocolate. So when the subjects took an ounce of chocolate is did not produce the desired result as the measurement was not correct. She can change the measurements of the chocolate to see the desired result.