Скачать или смотреть 4. Avoiding Bias

Introduction to Experimental Design
Training session with Dr Helen Brown, Senior Statistician, at The Roslin Institute, January 2016.
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These training sessions were given to staff and research students at the Roslin Institute. The material is also used for the Animal Biosciences MSc course taught at the Institute.
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*Recommended YouTube playback settings for the best viewing experience: 1080p HD
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Content:

Bias
-Bias = systematic inaccuracy in a measurement in one direction
---Eg Shared environment:
-Animals at Farm 1 have Treatment A and at Farm 2 have Treatment B
---Farm conditions affect measurements
-Animals in Cage 1 have Treatment A and in Cage 2 have Treatment B
---Cage conditions (eg daylight, temperature) affect measurements

Bias - examples
-Bias - examples: Shared environment
-Does temperature affect stem cell development?
---Observations on individual tissues are not independent
-Animals allocated to interventions haphazardly
---Picking mice one-by-one from container
---Giving first 10 treatment A and second 10 treatment B
-Researcher influenced by prior knowledge of an intervention
---Eg scoring animal behaviour