NIDS-CRAM is a computer-assisted telephonic interview (CATI) survey, designed to evaluate the socio-economic and health outcomes of COVID-19 inspired lockdowns in South Africa (SA). This paper conducts an analysis of attrition (or unit nonresponse) between Waves 1 and 2 of the National Income Dynamics Study-Coronavirus Rapid Mobile Survey (NIDS-CRAM). This is a new contribution to the South African literature on attrition and shows the importance of using paradata to understand nonresponse. Attrition was not influenced by how often respondents previously participated or refused in NIDS, the interviewer-interviewee experience in the interview or by the respondent's observable demographic characteristics. Another important finding was that respondents who underwent COVID-19 tests were 3% more likely to attrite, a trend that could negatively affect the efficacy of the survey to track COVID-19 testing behaviour in future waves. In the fully specified model, attrition was most affected by contact effort by the survey organisation, the sample batch the respondent was in during Wave 1, employment status and whether they had a missing value for household income. We fit probit regression models to predict the determinants of attrition. The number of successfully interviewed respondents reduced from 7,073 in Wave 1 of NIDS-CRAM to 5,676 in Wave 2-a level of attrition of almost 20%. You can find out more on the depositional landform geotopic.We introduce a new approach to the analysis of attrition in South African longitudinal surveys by supplementing the public-use data with paradata about the survey process and interview experience. It happens because wave have less energy. Solution - material is disolved and carried by the water.ĭeposition is when eroded material is dropped by constructive waves. Suspension - beach material is suspended and carried by the waves. Saltation - beach material is bounced along the sea floor. Traction - large material is rolled along the sea floor. Material in one place is eroded, transported then deposited elsewhere.Īlthough longshore drift is the main process of transportation the material moves in four different ways. Longshore drift provides a link between erosion and deposition. This process slowly moves material along the beach. The backwash carries material back down the beach at right angles. The swash (waves moving up the beach) carries material up and along the beach. Longshore drift happens when waves moves towards the coast at an angle. Longshore drift is the movement of material along the shore by wave action. The movement of material along the coast is called longshore drift. Transportation is the movement of material in the sea and along the coast by waves. You can find out about the landforms created as the result of coastal erosion here. You can view animations of each of these processes here (this will open in a new window/tab). This process is known as hydraulic action.Īttrition is when waves cause rocks and pebbles to bump into each other and break up.Ĭorrosion/solution is when certain types of cliff erode as a result of weak acids in the sea. Often this causes cliff material to break away. When the wave retreats the air rushes out of the gap. When waves hit the base of a cliff air is compressed into cracks. It is commonly known as the sand paper effect. pebbles) and hurl them at the base of a cliff.Ībrasion occurs as breaking waves which contain sand and larger fragments erode the shoreline or headland. These are corrasion, abrasion, hydraulic action, attrition and corrosion/solution.Ĭorrasion is when waves pick up beach material (e.g. There are five main processes which cause coastal erosion. This often involves destructive waves wearing away the coast. What is coastal erosion?Įrosion is the wearing away of the land by the sea. These are erosion, transportation and deposition. There are three main processes at work in the sea. View videos of coastal environments in the video gallery. View images of coastal environments in the coastal gallery. Right click on the link above and select save link as : n Audio file for playback on mobile devices and personal computers You are here: home > geotopics > coasts > coastal processes
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