When the development of the same subject is studied over a period of time, the study is called :

Question

Accepted Answer

The study of the development of the same subject over a period of time is called a "Longitudinal study." This type of study is specifically designed to observe changes and developments in the same subjects over an extended period. Here’s why Option 4 is the correct answer and why the other options are incorrect:

1. **Longitudinal Study (Correct Answer):** 
   - A longitudinal study involves repeated observations of the same variables, such as individuals or groups, over a long period. This method is particularly useful for studying changes and developments over time, such as growth, aging, or the progression of diseases. It allows researchers to detect developments or changes in the characteristics of the target population at both the group and the individual level.

2. **Life History Study (Incorrect):**
   - A life history study focuses on the comprehensive and detailed account of an individual's life experiences. While it may cover a long period, it is more qualitative and narrative in nature, often used in anthropology or sociology to understand the life course of an individual rather than systematically studying changes over time in a broader subject.

3. **Survey Study (Incorrect):**
   - A survey study involves collecting data from a sample of individuals at a single point in time to infer characteristics or opinions of a larger population. It is not designed to track changes over time, making it unsuitable for studying the development of a subject over a period.

4. **Cross-sectional Study (Incorrect):**
   - A cross-sectional study examines data from a population, or a representative subset, at one specific point in time. It provides a snapshot of a particular moment, which is useful for identifying associations but not for observing changes over time. Unlike longitudinal studies, cross-sectional studies do not follow the same subjects over a period.

In conclusion, a longitudinal study is the most appropriate method for studying the development of the same subject over time, as it allows for the observation of changes and trends within the same group of subjects. This makes Option 4 the correct answer.