2.4 bias in surveys. statistical bias is any factor that favours certain outcomes or responses and...
TRANSCRIPT
2.4 Bias in Surveys
• Statistical bias is any factor that favours certain outcomes or responses and hence systematically skews the survey results.
Sampling Bias
• The sampling frame does not reflect the characteristics of the population.
• For example: a Survey asked students of a hockey team to see if the school should pay for all student’s equipment.
Non-Response Bias
• Occurs when certain groups are under represented in the survey because they choose not to participate.
• A researcher asks every 5th student entering the cafeteria to fill out a survey. Less than half agree to fill out the questionnaire.
Response Bias• Occurs when participants in a survey
deliberately give false or misleading answers. The respondents might want to influence the results unduly, or they may be afraid or embarrassed to answer sensitive questions honestly.
• After a lesson, a teacher says “raise your hands if you do not understand”
Measurement Bias
• Occurs when the data collection method consistently either under or overestimates a characteristic of the population
• A police officer tries to survey traffic speeds by patrolling the highway and recording the speeds of cars around them.
Leading question
• Directs the person’s response through limitation.
Loaded question
• Influences a person’s response through inflammation.
Uses and Misuses of Sample Data
Bias can be unintentional
• In other cases, a person could intentionally manipulate the data management process in an attempt to affect the results.
• This happens in advertising on occasion…
A company’s profit increased from $400.00 to $600.00 per
month
TV sales doubled from 2500 to 5000 units.
year
Number of Bookings at Ski Resorts
Homework
• Page 123
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