In statistics, marketing and demography, a cohort is a group of subjects who share a defining characteristic (typically subjects who experienced a common event in a selected time period, such as birth or graduation).
Case–control study versus cohort on a timeline. "OR" stands for "odds ratio" and "RR" stands for "relative risk".
Cohort data can oftentimes be more advantageous to demographers than period data. Because cohort data is honed to a specific time period, it is usually more accurate. It is more accurate because it can be tuned to retrieve custom data for a specific study.
In addition, cohort data is not affected by tempo effects, unlike period data. On the contrary, cohort data can be disadvantageous in the sense that it can take a long amount of time to collect the data necessary for the cohort study.[1] Another disadvantage of cohort studies is that it can be extremely costly to carry out, since the study will go on for a long period of time, demographers often require sufficient funds to fuel the study.
Demography often contrasts cohort perspectives and period perspectives. For instance, the total cohort fertility rate is an index of the average completed family size for cohorts of women, but since it can only be known for women who have finished child-bearing, it cannot be measured for currently fertile women. It can be calculated as the sum of the cohort's age-specific fertility rates that obtain as it ages through time. In contrast, the total period fertility rate uses current age-specific fertility rates to calculate the completed family size for a notional woman, were she to experience these fertility rates through her life.
Prospective Cohort Study: In this type of study, there is a collection of exposure data (baseline data) from the subjects recruited before development of the outcomes of interest. The subjects are then followed through time (future) to record when the subject develops the outcome of interest. Ways to follow-up with subjects of the study include: phone interviews, face-to-face interviews, physical exams, medical/laboratory tests, and mail questionnaires.[2] An example of a prospective cohort study is, for instance, if a demographer wanted to measure all the males births in the year 2018. The demographer would have to wait for the event to be over, the year 2018 must come to an end in order for the demographer to have all the necessary data.[3]
Retrospective Cohort Study: Retrospective Studies start with subjects that are at risk to have the outcome or disease of interest and identifies the outcome starting from where the subject is when the study starts to the past of the subject to identify the exposure. Retrospective use records: clinical, educational, birth certificates, death certificates, etc. but that may be difficult because there may not be data for the study that is being initiated. These studies may have multiple exposures which may make this study difficult.[4] On the other hand, an example of a retrospective cohort study is, if a demographer was examining a group of people born in year 1970 who have type 1 diabetes. The demographer would begin by looking at historical data. However, if the demographer was looking at ineffective data in attempts to deduce the source of type 1 diabetes, the demographers results would not be accurate.[1]
Centre for Longitudinal Studies - the UK resource centre for national birth cohort studies.
January 20, 2023
cohort, statistics, other, senses, this, word, cohort, disambiguation, statistics, marketing, demography, cohort, group, subjects, share, defining, characteristic, typically, subjects, experienced, common, event, selected, time, period, such, birth, graduation. For other senses of this word see cohort disambiguation In statistics marketing and demography a cohort is a group of subjects who share a defining characteristic typically subjects who experienced a common event in a selected time period such as birth or graduation Case control study versus cohort on a timeline OR stands for odds ratio and RR stands for relative risk Cohort data can oftentimes be more advantageous to demographers than period data Because cohort data is honed to a specific time period it is usually more accurate It is more accurate because it can be tuned to retrieve custom data for a specific study In addition cohort data is not affected by tempo effects unlike period data On the contrary cohort data can be disadvantageous in the sense that it can take a long amount of time to collect the data necessary for the cohort study 1 Another disadvantage of cohort studies is that it can be extremely costly to carry out since the study will go on for a long period of time demographers often require sufficient funds to fuel the study Demography often contrasts cohort perspectives and period perspectives For instance the total cohort fertility rate is an index of the average completed family size for cohorts of women but since it can only be known for women who have finished child bearing it cannot be measured for currently fertile women It can be calculated as the sum of the cohort s age specific fertility rates that obtain as it ages through time In contrast the total period fertility rate uses current age specific fertility rates to calculate the completed family size for a notional woman were she to experience these fertility rates through her life A study on a cohort is a cohort study Two important types of cohort studies are Prospective Cohort Study In this type of study there is a collection of exposure data baseline data from the subjects recruited before development of the outcomes of interest The subjects are then followed through time future to record when the subject develops the outcome of interest Ways to follow up with subjects of the study include phone interviews face to face interviews physical exams medical laboratory tests and mail questionnaires 2 An example of a prospective cohort study is for instance if a demographer wanted to measure all the males births in the year 2018 The demographer would have to wait for the event to be over the year 2018 must come to an end in order for the demographer to have all the necessary data 3 Retrospective Cohort Study Retrospective Studies start with subjects that are at risk to have the outcome or disease of interest and identifies the outcome starting from where the subject is when the study starts to the past of the subject to identify the exposure Retrospective use records clinical educational birth certificates death certificates etc but that may be difficult because there may not be data for the study that is being initiated These studies may have multiple exposures which may make this study difficult 4 On the other hand an example of a retrospective cohort study is if a demographer was examining a group of people born in year 1970 who have type 1 diabetes The demographer would begin by looking at historical data However if the demographer was looking at ineffective data in attempts to deduce the source of type 1 diabetes the demographers results would not be accurate 1 See also EditAge grade Bureau of Labor Statistics Case mix Cohort study Generational cohort National Longitudinal Surveys Prospective cohort studyReferences Edit a b Advantages and Disadvantages of Cohort Studies sphweb bumc bu edu Retrieved 2018 03 27 Cohort Studies sphweb bumc bu edu Retrieved 2017 04 04 Statistical Analysis Handbook www statsref com Retrieved 2018 04 05 Cohort Studies sphweb bumc bu edu Retrieved 2017 04 04 External links EditCohort in a glossary U S Bureau of Labor Statistics Division of Information Services Centre for Longitudinal Studies the UK resource centre for national birth cohort studies Retrieved from https en wikipedia org w index php title Cohort statistics amp oldid 1121511343, wikipedia, wiki, book, books, library,
