Inter-Rater or Inter-Observer Reliability It is possible to have a reliable measure that is not valid, however a valid measure must also be reliable.Below are some of the forms of reliability that the researcher will need to address Reliability is an essential pre-requisite for validity. There are many forms of reliability, all of which will have an effect on the overall reliability of the instrument and therefore the data collected. Reliability in research data refers to the degree to which an assessment consistently measures whatever it is measuring. In order for the results from a study to be considered valid, the measurement procedure must first be reliable. ![]() Reliability, like validity, is a way of assessing the quality of the measurement procedure used to collect data in a dissertation. This ensures that all of the samples represent the same area or volume (water) of the habitat each time. Samples are usually taken using a standard sampling unit of some kind. In order to be reasonably sure that the results from the samples do represent the habitat as closely as possible, careful planning beforehand is essential. This problem is usually solved by taking a number of samples from around the habitat, making the necessary assumption that these samples are representative of the habitat in general. It would be like trying to count different sizes and colors of grains of sand on the beach. If we want to know what kind of plants and animals are in a particular habitat, and how many there are of each species, it is usually impossible to go and count each and every one present. ![]() We can broadly group factors influencing ecosystems in to: biotic factors are living factors affecting an organism, such as food, competition or disease and abiotic factors, non-living factors. Investigations in to ecosystems are very complicated since there are so many different factors that need to be considered. Ecosystems can be better understood through the investigation and quantification of their components.The description and investigation of ecosystems allows for comparisons to be made between different ecosystems and for them to be monitored, modelled and evaluate over time, measuring both natural change and human impacts.In this unit you will learn how to make dichotomous keys to identify organisms and various sampling techniques. It can also be a challenge trying to find out how many anthills are in a 100 square kilometers. Especially if the organism you are trying to sample is traveling over 50km per hour. Measuring the biotic component can be a challenge at times. ![]() Remember that biotic components of an ecosystems consists of all of the living organisms in the ecosystem. To make links between the physical environment and the biotic communities, ecologist and environmental scientist need to be able to measure the abiotic conditions. In terrestrial ecosystems physical conditions in the atmosphere, at the surface and within the soils all interact to create the conditions that give rise to vegetation that develops. To a large extent it is the physical (abiotic) conditions within any environment that controls the plant and thus the animal (biotic) community that develops.
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