why are some narrative of slave consider bias by historian?

Because most historians back then were white (because blacks werent allowed to go to school). This left many biast things about the slave system and slave trade.

does anyone can provide me a website for this issue? i cannnot find them when search with google.

Not all of these, but some address bias in slave narratives:

http://www.google.com/search?q=%22slave+narratives%22+biased&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7SUNA

Remember -- each of us tells a story from our own points of view. Each person's point of view is his or her bias.

Some narratives of slavery are considered biased by historians because they may have been influenced by the perspectives and biases of the authors themselves. When studying history, it is crucial to critically examine the sources of information and recognize that different individuals may have different agendas, beliefs, and viewpoints.

To understand why certain slave narratives may be considered biased, historians look at a few key factors:

1. Author's background: The background, social status, and personal experiences of the author can shape their narrative. For example, if a white slave owner wrote a narrative about the institution of slavery, their perspective might be influenced by their own self-interest or desire to justify their actions.

2. Influences and intended audience: The intended audience of a narrative can influence its content. Some narratives were written with the goal of promoting a particular cause or advocating for the abolition of slavery. These narratives may emphasize certain aspects or incidents to evoke empathy or support. Others were tailored to appeal to a particular readership or fit specific ideological agendas.

3. Reliability of sources: Historians evaluate the reliability of the sources used in slave narratives. Some authors relied on their own memory, which can be fallible or influenced by personal biases. Additionally, the circumstances under which these narratives were produced, such as the pressure to conform to certain societal expectations, may also affect their accuracy.

4. Omissions and distortions: Biases can manifest through intentional or unintentional omissions or distortions in the narratives. Authors may leave out certain details, events, or perspectives that do not align with their portrayal of slavery. They may also exaggerate or misrepresent incidents to reinforce their own arguments or agendas.

To overcome this bias, historians rely on a variety of sources and compare multiple perspectives. They carefully examine primary sources, such as letters, diaries, court records, and other contemporary accounts, to corroborate or challenge the narratives in question. By doing so, historians strive to provide a more comprehensive, nuanced understanding of the institution of slavery and its impact on individuals and societies.