A disadvantage of longitudinal studies is that

Explanation:

unpredictability always present.

Because longitudinal studies involve the same subjects over a long period, what happens to them outside of the data collection moments can influence future data being collected. Some people may choose to stop participating in the research. Others may no longer find themselves in the correct demographics for the research. If these factors are not included in the initial design of the research, then it could invalidate the findings that are produced.

2. It takes time.

Researchers involved with longitudinal studies may never see the full outcome of their work. It may take several years before the data begins producing observable patterns or relationships that can be tracked. That means the ability to maintain open lines of communication with all researchers is vitally important to the eventual success of the study.

3. The data gathered by longitudinal studies is not always accurate or reliable.

It only takes one piece of unreliable or inaccurate data to possibly invalidate the findings that the longitudinal studies produce. Because humans have their own personal bias toward certain subjects, the researcher processing the data may unconsciously alter the data to produce intended results.

4. It relies on the skills of the researchers to be complete.

Because data collection occurs in real-time and relies heavily on the skills of the researchers who are tasked with this job, the quality of the data is heavily reliant on those skills. Two different researchers