Examine the issue of having a young-adult for a narrator. Do you think this makes Anne more or less reliable ? How is her perspective on the world and her experiences different than an adults? Would the novel's impact have been greater or worse if an adult had written the novel? Use specific examples from the novel to support your analysis.

The Diary of a Young Girl is a collection of writings by Anne Frank, a Dutch girl who hid in an annex with her Jewish family during the Nazi occupation of the Netherlands. The diary reveals Anne's innocence, idealism, intelligence, and sense of human morality even in the context of widespread horror.
First, let me provide a bit of background so that we understand Anne's situation and age when she wrote the text. Anne started keeping the diary in June 1942, just days after her 13th birthday. She kept writing in it for two years, until the family (and a handful of colleagues and friends that were hiding with them) were discovered and sent to concentration camps. Anne died at Bergen-Belsen at age 15. 
Let us go over a few of the ways that a young adult narrator (versus an adult narrator) sets the tone of the text by touching on the questions of reliability and effect on the audience.
Innocence
Anne is just 13 when she starts writing in the diary. There is plenty that she cannot know about the world (or the exact situation she is in) at this age, simply because she is young. She knows that she is young and that no one will likely be interested in her thoughts:

Writing in a diary is a really strange experience for someone like me. Not only because I’ve never written anything before, but also because it seems to me that later on neither I nor anyone else will be interested in the musings of a thirteen-year old school girl. Oh well, it doesn’t matter. I feel like writing.

However, she is perceptive. She serves as an advocate for young people and the importance of speaking up:

We aren’t allowed to have any opinions. People can tell you to keep your mouth shut, but it doesn’t stop you having your own opinion. Even if people are still very young, they shouldn’t be prevented from saying what they think.

It is important to note that Anne does not only write about political or social issues. She also writes about subjects that would be of interest or concern to any girl of her age:

There are little folds of skin all over the place, you can hardly find it. The little hole underneath is so terribly small that I simply can't imagine how a man can get in there, let alone how a whole baby can get out!

Passages like this remind us that Anne is young. Even in the face of the Holocaust, she is going through the regular stages of puberty and adolescence. Her innocence and curiosity makes her seem human and relatable.
Idealism
Anne is idealistic about human nature, which stands in contrast to what we might expect from an adult narrator who might be more jaded about the world and what terrible things people can do to each other.


It’s difficult in times like these: ideals, dreams and cherished hopes rise within us, only to be crushed by grim reality. It’s a wonder I haven’t abandoned all my ideals, they seem so absurd and impractical. Yet I cling to them because I still believe, in spite of everything, that people are truly good at heart.


Reliability
 
Is Anne a more reliable narrator than an adult narrator would be? This depends, in part, on your personal reading of the diary. On one hand, Anne is too young to understand the historical context of the Holocaust; it also seems impossible that she could understand what a terrible fate awaited her (she died of typhus in a concentration camp) because her parents were trying to protect her. In this sense, she is not as "reliable" as an adult narrator.
 
On the other hand, Anne has a propensity for honesty and transparency that an adult narrator might not be able to match. Note the inscription that Anne wrote inside the diary's front cover:

I hope I will be able to confide everything to you, as I have never been able to confide in anyone, and I hope you will be a great source of comfort and support.

Anne is not self-conscious or trying to present herself in a certain way, as an adult might do. She is reliable because she is being completely honest about her own feelings and her view of the world around her. This viewpoint, and this representation of the personal experience of a Holocaust victim, is what makes Anne's diary so unique and valuable to so many people around the world.