PPCA is a global association dedicated to the ongoing creation and distribution of technical and application information on plastic pipes system in order to educate and expand their safe, cost effective and sustainable use. Pipes were extruded using both approaches and properties were evaluated per the relevant ASTM and ISO standards for water and gas pressure pipe applications to compare the performance of extruded pipes. The results show that when high quality pipes are produced, the performance of pipes made via either in-line compounding or a pre-compound, is equivalent. The catalyst is based on two different metallocene components, whereas one component doesn't incorporate any co-monomer and the other component shows a typical homogenous co-monomer distribution.
This simultaneous data gathering is often thought of as a snapshot of conditions present at that instant. Its most important application lies in the field of epidemiology and disease research.
Although it offers several advantages, such as the ease of assessing the prevalence of diseases, a cross-sectional study nevertheless has limitations. Ease of Data Gathering and Assessment The nature of cross-sectional studies offers a quick and easy way for an epidemiologist or any kind of researcher to quickly amass data.
While some special case studies do require more specific data, for most cross-sectional studies, routinely collected data will suffice. This allows for quick and easy data gathering even for a large target population.
Assessment of outcomes and risk factors for the entire population is also done with little trouble, as the sample is a near-perfect snapshot of the whole. Low to Moderate Cost The ease of gathering the needed information translates to cost-effectiveness.
Many hospitals and census bureaus have that information already in hand, saving the researcher the trouble of gathering it, a time-consuming and expensive activity.
Two distinct variables are measured at the same point in time. Cross-sectional studies can say that the two are related somehow, but they cannot positively determine if one caused the other.
Cross-sectional studies also fail on the part of confounding factors. Additional variables may affect the relationship between the variables of interest but not affect those variables themselves. Such observations are often lost in cross-sectional studies.
Neyman Bias This limitation stems from the tools used for data gathering, either by the researcher himself or by hospital or census bureau employees. Tools such as pedometers, scales and sphygmomanometers are more or less accurate, but the most common tools used for data gathering, questionnaires, introduce a prevalence-incidence bias known as the Neyman bias.
Even if the researcher uses a completely objective questionnaire, the person answering cannot answer questions involving past events with perfect accuracy. Cross-sectional studies About the Author Natalie Andrews has been writing since She has created content for print newsletters and blogs in the flower, transportation and entertainment industries.
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Sep 22, · Longitudinal studies require enormous amounts of time and are often quite expensive. Because of this, these studies often have only a small group of subjects, which makes it difficult to apply the results to a larger srmvision.com: Resolved.
NHLBI ARDS Network | Publications Publications. A longitudinal study, like a cross-sectional one, is observational. So, once again, researchers do not interfere with their subjects. However, in a longitudinal study, researchers conduct several observations of the same subjects over a period of time, sometimes lasting many years.
The Pros and Cons of Longitudinal Research. Share Flip Email Search the site GO. Longitudinal research is often contrasted with cross-sectional research; Longitudinal research involves collecting data over an extended period, often years or even decades The Pros and Cons of International Medical Schools.
List. Pros And Cons Of Cross Sectional And Longitudinal Approaches Discuss the Pros and Cons of Cross - sectional and Longitudinal approaches to the study of development The study of development is that of changes in physical, cognitive, social and emotional capabilities over time.