What is centripetal bias?
The reputations of certain clinicians and institutions cause individuals with specific disorders or exposures to gravitate toward them.
What are the three types of bias in epidemiology?
Define bias (systematic error) and differentiate between the three types of bias: selection bias, misclassification/information bias, and confounding bias.
What are the two major types of bias in epidemiological studies?
More than 50 types of bias have been identified in epidemiological studies, but for simplicity they can be broadly grouped into two categories: information bias and selection bias.
What is participation bias in epidemiology?
Participation bias or non-response bias is a phenomenon in which the results of elections, studies, polls, etc. become non-representative because the participants disproportionately possess certain traits which affect the outcome.
What is meant by referral bias?
Referral bias (admission rate bias) refers to a situation where the chance of exposed cases being admitted to the study is different to exposed controls. This happens frequently when cases are selected in a hospital whose activity is linked to the studied exposure.
What is sampling bias in healthcare?
Sampling bias is a type of selection bias. It occurs when the method used to sample the population means that some members of the intended population are more likely to be selected than others.
What is the difference between confounding and bias?
Confounding can produce either a type 1 or a type 2 error, but we usually focus on type 1 errors. Bias creates an association that is not true, but confounding describes an association that is true, but potentially misleading.
What is the difference between selection bias and confounding?
While inadequate control of confounding is the most-often cited source of potential bias, selection bias which arises when patients are differentially excluded from analyses is a distinct phenomenon with distinct consequences: confounding bias compromises internal validity while selection bias compromises external …
What is recall bias in epidemiology?
Recall bias occurs when participants in a study are systematically more or less likely to recall and relate information on exposure depending on their outcome status, or to recall information regarding their outcome dependent on their exposure.
What is lead time bias in epidemiology?
Lead-time bias occurs when a disease is detected by a screening or surveillance test at an earlier time point than it would have been if it had been diagnosed by its clinical appearance; this time lag or “lead time” during which the disease is asymptomatic is not taken into account during the survival analysis (Figure …
What is a confounding bias?
Confounding bias: A systematic distortion in the measure of association between exposure and the health outcome caused by mixing the effect of the exposure of primary interest with extraneous risk factors.
What is the difference between sampling bias and selection bias?
A distinction, albeit not universally accepted, of sampling bias is that it undermines the external validity of a test (the ability of its results to be generalized to the entire population), while selection bias mainly addresses internal validity for differences or similarities found in the sample at hand.
Which type of sampling is most vulnerable to bias?
Which type of sampling is most vulnerable to bias? Rationale: Although it is the most widely used approach for quantitative researchers, convenience sampling is the most vulnerable to sampling biases.
What are the 4 types of bias in statistics?
Types of selection bias include: the healthy worker effect, non-response bias, undercoverage, and voluntary response bias.
What is confounding in epidemiology?
Confounding is the distortion of the association between an exposure and health outcome by an extraneous, third variable called a confounder.
How is confounding controlled in epidemiology?
Strategies to reduce confounding are:
- randomization (aim is random distribution of confounders between study groups)
- restriction (restrict entry to study of individuals with confounding factors – risks bias in itself)
- matching (of individuals or groups, aim for equal distribution of confounders)
Do confounders cause selection bias?
Confounding factors, if not controlled for, cause bias in the estimate of the impact of the exposure being studied. The effects of confounding can result in: * An observed difference between study populations when no real difference exists.
What are the measures of central location in epidemiology?
Three measures of central location are commonly used in epidemiology: arithmetic mean, median, and mode. Two other measures that are used less often are the midrange and geometric mean. All of these measures will be discussed later in this lesson.
What is the central location of a frequency distribution?
The clustering at a particular value is known as the central location or central tendency of a frequency distribution. The central location of a distribution is one of its most important properties. Sometimes it is cited as a single value that summarizes the entire distribution.
What are the principles of Epidemiology?
Principles of epidemiology, 2nd ed. Atlanta: U.S. Department of Health and Human Services;1992. The process begins with the appropriate exposure to or accumulation of factors sufficient for the disease process to begin in a susceptible host.
What is the difference between measures of central location and spread?
Just as measures of central location describe where the peak is located, measures of spread describe the dispersion (or variation) of values from that peak in the distribution. Measures of spread include the range, interquartile range, and standard deviation.