Attrition
Attrition - Related Videos
02:20
Longitudinal Research
0 Views •
2020
Sometimes we want to see how people change over time, as in studies of human development and lifespan. When we test the same group of individuals repeatedly over an extended period of time, we are conducting longitudinal research. Longitudinal research is a research design in which data-gathering is administered repeatedly over an extended period of time. For example, we may survey a group of individuals about their dietary habits at age 20, retest them a decade later at age 30, and then again...
07:55
The Optical Fractionator Technique to Estimate Cell Numbers in a Rat Model of Electroconvulsive Therapy
0 Views •
Cited by 24 •
2017
Here, we present a stereological method, the optical fractionator, used to quantify the formation of new neurons, and their survival, in the rat hippocampus following electroconvulsive stimulation. When correctly implemented, the sensitivity and efficiency of stereological methods ensures accurate estimates with a fixed and predetermined precision.
09:13
Characterization of Ultra-fine Grained and Nanocrystalline Materials Using Transmission Kikuchi Diffraction
0 Views •
Cited by 8 •
2017
This paper provides a detailed method to characterize the microstructure of ultra-fine grained and nanocrystalline materials using a scanning electron microscope equipped with a standard electron backscatter diffraction system. Metal alloys and minerals presenting refined microstructures are analyzed using this technique, showing the diversity of its possible applications.
10:42
Chromosomal Spread Preparation of Human Embryonic Stem Cells for Karyotyping
0 Views •
Cited by 33 •
2009
Karyotyping is a simple and useful technique widely used for detecting genetic alterations. Here we describe a step by step protocol for chromosome spread preparation of human embryonic stem cells for monitoring the chromosomal status of these cells maintained in culture.
10:02
Applications of pHluorin for Quantitative, Kinetic and High-throughput Analysis of Endocytosis in Budding Yeast
0 Views •
Cited by 18 •
2016
Accurate quantification of vesicular trafficking events often provides key insights into roles for specific proteins and the effects of mutations. This paper presents methods for using superecliptic pHluorin, a pH-sensitive GFP variant, as a tool for quantification of endocytic events in living cells using quantitative fluorescence microscopy and flow cytometry.
FAQs
The first interpretive step is to classify each loss according to its likely source. Mortality, emigration, predation, environmental stress, and cellular damage represent biological processes, whereas dropout or sample degradation may reflect study design or handling. Separating these categories helps researchers determine whether an observed decline reflects biology, experimental conditions, or both.
Different causes imply different biological meanings and require different interpretations. A population decline associated with mortality may indicate reduced survival, while emigration changes the number observed without necessarily indicating death. Likewise, cellular damage can alter culture results, whereas degraded experimental material can reduce data quality. Identifying the cause prevents unrelated losses from being treated as one process.
Attrition changes the number of individuals available for observation and can therefore influence estimates of population size and survival. Population models become more informative when researchers consider whether losses arise from mortality, emigration, predation, or environmental stress. This distinction helps separate changes in population dynamics from changes caused by who remains observable.
The relevant factors depend on the system being studied. Populations may experience losses associated with mortality, emigration, predation, or environmental stress. Cell cultures may be affected by cellular damage, while biological samples can deteriorate during a study or through handling. Recording the context of each loss allows researchers to relate attrition to the appropriate biological or experimental condition.
A practical assessment begins by identifying the biological unit being followed, such as an individual, cell culture, or sample. Researchers then record losses over time, classify their likely causes, and compare those losses with the measured change in population size, biological function, or sample quality. This workflow supports clearer interpretation of longitudinal and experimental results.
Longitudinal studies repeatedly assess the same biological subjects or materials, so losses can reduce the information available at later time points. Tracking attrition shows whether a changing result reflects genuine biological change or the progressive loss of individuals, cells, or samples. This is especially important when evaluating survival, biological function, or trends over time.
In cell-based experiments, cellular damage or loss of culture material can change the apparent biological response independently of the process under investigation. Assessing attrition helps researchers judge whether reduced cell numbers or altered function reflect the intended experimental condition or damage occurring during the experiment. That distinction improves interpretation of cell culture outcomes.
Attrition assessments identify when sample degradation or experimental dropout may limit the strength of a conclusion. By documenting these losses, researchers can distinguish reduced sample quality from a genuine biological effect and recognize how study design or handling influenced the dataset. The resulting interpretation is better aligned with the material actually available for analysis.