Often research designs both qualitative and quantitative can also be classified based on time elements inluding the duration and the direction of the time.

Research Design For Duration

Cross-sectional study:

A cross-sectional study is a type of observational study, or descriptive research, that involves analyzing information about a population at a specific point in time. In this type of study, the research studies a stratified group of subjects at one point in time, data is collected once during a single point in time or a limited time interval. The conclusion is drawn about development within a population by comparing the characteristics of those strata.

In a cross-sectional study, the variables remain the same throughout. This makes it useful in many sectors and circumstances, mainly in financial and healthcare areas. Here are the few examples: for analyzing spending trends, for GDP measurement, for measuring the spread of disease, for educational research, for financial datasheets.[1] [7]

Longitudinal study:

In this study the researcher follows a cohort of subjects over time, performing repeated measurements at prescribed intervals. Because the same individuals are tested throughout the study, personal characteristics remain relatively constant and differences observed over time are interpreted as a developmental change. [6]

Examples of famous longitudinal studies: [2]

1.Grant Study- Duration: 1942-Present. The Grant Study is one of the most ambitious longitudinal studies. It attempts to answer a philosophical question that has been central to human existence since the beginning of time – what is the secret to living a good life?

• It does so by studying the lives of 268 male Harvard graduates who are interrogated at least every two years with the help of questionnaires, personal interviews, and gleaning information about their physical and mental well-being from their physician.

• Begun in 1942, the study continues to this day. The study has provided researchers with several interesting insights into what constitutes the human quality of life.

• For instance:

  • • It reveals that the quality of our relationships is more influential than IQ when it comes to our financial success.

    • It suggests that our relationships with our parents during childhood have a lasting impact on our mental and physical well-being until late into our lives.

• In short, the results gleaned from the study (so far) strongly indicate that the quality of our relationships is one of the biggest factors in determining our quality of life.

2. Terman Life Cycle Study: Duration: 1921-Present o The Terman Life-Cycle Study, also called the Genetic Studies of Genius, is one of the longest studies ever conducted in the field of psychology.

• Commenced in 1921, it continues to this day, over 100 years later!

• The objective of the study at its commencement in 1921 was to study the life trajectories of exceptionally gifted children, as measured by standardized intelligence tests.

• Lewis Terman, the principal investigator of the study, wanted to dispel the then-prevalent notion that intellectually gifted children tended to be:

  • • socially inept,

    • and physically deficient

• To this end, Terman selected 1528 students from public schools in California based on their scores on several standardized intelligence tests such as the Stanford-Binet Intelligence scales, National Intelligence Test, and the Army Alpha Test.

• It was discovered that intellectually gifted children had the same social skills and the same level of physical development as other children.

• As the study progressed, following the selected children well into adulthood and in their old age, it was further discovered that having higher IQs did not affect outcomes later in life in a significant way (Terman & Oden, 1959).

3. The Study of Mathematically Precocious Youths: Duration: 1971-Present o The Study of Mathematically Precocious Youths (SMPY) is a longitudinal study initiated in 1971 at the Johns Hopkins University.

• At the time of its inception, the study aimed to study children who were exceptionally gifted in mathematics as evidenced from their Scholastic Aptitude Test (SAT) scores.

• Later the study shifted to Vanderbilt University and was expanded to include children who scored exceptionally high in the verbal section of the SATs as well.

• The study has revealed several interesting insights into the life paths, career trajectories, and lifestyle preferences of academically gifted individuals.

• For instance, it revealed:

  • • Children with exceptionally high mathematical scores tended to gravitate towards academic, research, or corporate careers in the STEM fields.

    • ▪ Children with better verbal abilities went into academic, research, or corporate careers in the social sciences and humanities

4. Baltimore Longitudinal Study of Aging: Duration: 1958 to Present o The Baltimore Longitudinal Study of Aging (BLSA) was initiated in 1958 to study the effects of aging, making it the longest-running study on human aging in America.

• With a sample size of over 3200 volunteer subjects, the study has revealed crucial information about the process of human aging.

• For instance, the study has shown that:

  • • The most common ailments associated with the elderly such as diabetes, hypertension, and dementia are not an inevitable outcome of growing old, but rather result from genetic and lifestyle factors.

    • Aging does not proceed uniformly in humans, and all humans age differently. Study Design by direct.

Research Design for Direction

Retrospective Study:

This type of research design involves the examination of data that have been collected in the past, often obtained from medical records or surveys. A retrospective study is an observational study that enrolls participants who already have a disease or condition. In other words, all cases have already happened before the study begins. Researchers then look back in time, using questionnaires, medical records and other methods; Basically, you just dig into the data and see what you find. The goal is to find out what potential risk factors or other associations and relationships the group has in common.[3] [4] [5]

Examples of retrospective study: A group of 100 people with AIDS might be asked about their lifestyle choices and medical history in order to study the origins of the disease.

• Another example of One of the first recognized retrospective cohort studies was Lane-Claypon’s 1926 study of breast cancer risk factors, titled “A Further Report on Cancer of the Breast, With Special Reference to Its Associated Antecedent Conditions.” The study of 500 hospitalized patients and 500 controls led to the identification of most of the risk factors for breast cancer that we know today.

Prospective Study:

This type of research design involves the measurement of variables through direct recording in the present. The researcher follows subjects as they progress through their intervention or trial. A prospective study is an observational study where participants are enrolled before any of them have the disease or outcome being investigated. A prospective study takes a group of similar people (a cohort) and studies them over time. At the time the baseline data is collected, none of the people in the study have the condition of interest.

Once the prospective cohort study has been established, researchers follow up with the participants and track their progress. [3] [4] [5]

Follow ups can be:

• In-person interviews.

• Imaging tests. • Internet questionnaires.

• Lab tests.

• Mail questionnaires.

• Phone interviews.

Examples of prospective study: a group of 100 people with high risk factors for AIDS are followed for 20 years to see if they develop the disease. • Another example of famous prospective cohort study is Framingham Study. Framingham Study is a population-based, prospective cohort study that was initiated by United States Public Health Service in 1948 to prospectively investigate the epidemiology and risk factors for cardiovascular disease. It has grown into an ongoing longitudinal study gathering prospective data on a wide a variety of biological and lifestyle risk factors and on cardiovascular, neurological and other types of disease outcomes across three generations. [3] [4] [5]

[1] 4 Cross-Sectional Study Examples (With Traits and Types) | Indeed.com

[2] 10 Famous Examples of Longitudinal Studies (2022) (helpfulprofessor.com)

[3] Retrospective Study: Definition & Examples - Statistics By Jim

[4] Cohort Study (Retrospective, Prospective): Definition, Examples - Statistics How To

[5] Methodology Series Module 1: Cohort Studies - PMC (nih.gov)

[6] What is a Longitudinal Study? - Definition with Examples (questionpro.com)

[7] Cross-Sectional Study | Definition, Uses & Examples (scribbr.com)