Introductory Statistics: Bias and Sampling Errors
Termini in questo insieme (20)
Sampling bias occurs when the technique used to select individuals favors one part of the population over another, making the sample unrepresentative.
Nonresponse bias happens when individuals selected for a sample do not respond and their opinions differ from those who do respond.
Response bias occurs when survey answers do not reflect the true feelings of the respondents.
Voluntary response bias arises when respondents decide themselves whether to participate, often leading to unrepresentative samples. Example: A TV show asking viewers to call in their opinions.
Undercoverage happens when some groups in the population are left out or inadequately represented in the sample.
Biased wording can mislead respondents or influence their answers, affecting the survey's accuracy.
Open questions allow respondents to answer freely; closed questions require choosing from predetermined options.
Sampling error is the discrepancy between a sample result and the true population result due to random selection.
Nonsampling error results from human mistakes, biased questions, false data, or inappropriate statistical methods, including undercoverage and response biases.
Nonrandom sampling error occurs when a nonrandom method like convenience or voluntary response sampling is used, causing bias.
Sample size is the number of items or subjects in a sample; larger sizes generally provide more reliable estimates.
Data should come from a reputable source to ensure accuracy and reliability.
The order of questions can influence how respondents interpret and answer subsequent questions, potentially biasing results.
A misleading conclusion occurs when sample data is reported instead of measured data or when answers are misrepresented.
Sampling error is due to random chance in sample selection; nonsampling error arises from mistakes or biases unrelated to sampling randomness.
Low response rates can increase nonresponse bias, reducing the representativeness of the sample.
Example: Asking "Do you oppose the reduction of estate taxes?" may bias answers compared to "Do you favor or oppose the reduction of estate taxes?"
The sampling method determines how individuals are selected; random methods reduce bias, while nonrandom methods increase it.
Because participants self-select, leading to overrepresentation of strong opinions and bias.
Bias causes systematic errors making samples unrepresentative; sampling error is random variation expected in any sample.