7.7 Quick review questions

A study on the bruising of apples (Doosti-Irani et al. 2016) aimed to determine the relationship between the recorded surface temperature of apple, the depth of bruising.

The researchers purposefully hit apples with three different forces (200, 700 and 1200 mJ) to inflict bruises.

The researchers then recorded the depth of the bruising, and recorded the surface temperature at each bruise location.

The study was conducted separately for three different regions of the apple (lower; middle; upper), and each apple was only used once.

1. The response variable is
   The force used on the apples The depth of the bruising The location of the bruising The surface temperature at the bruise
2. The explanatory variable is
   The force used on the apples The depth of the bruising The location of the bruising The surface temperature at the bruise
3. What is the best description for the variable ‘The location of the bruising?’
   A confounding variable, since it may be related to the explanatory variable only A confounding variable, since it may be related to the response variable and explanatory variables An extraneous variable, because it is likely to be related to the response variable only A lurking variable, since we don’t know how it might be related to the response and explanatory variables
4. True or false: The researchers could minimise the effects of confounding by incorporating potential confounding variables in the anaysis.
   TRUE FALSE
5. True or false: The researchers could use random allocation of the treatments to the applied to the apples to minimise confounding.
   TRUE FALSE
6. True or false: The carry-over effect is likely to be a big problem in this study.
   TRUE FALSE
7. True or false: The Hawthorne effect is likely to be a big problem in this study. TRUE FALSE
8. True or false: The placebo effect is likely to be a big problem in this study.
   TRUE FALSE
9. True or false: The observer effect is likely to be a big problem in this study. TRUE FALSE

References

Doosti-Irani O, Golzarian MR, Aghkhani MH, Sadrnia H, Doosti-Irani M. Development of multiple regression model to estimate the apple’s bruise depth using thermal maps. Postharvest Biology and Technology. Elsevier; 2016;116:75–9.

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Copyright © Peter K. Dunn, 2021