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In the answer of this question, a practical solution was suggested for:

Let $X_1, X_2, ..., X_k$ be a sequence of i.i.d. random variables with $X_i \sim \mathcal{U}\{1, 2, ..., n\}$ (discrete uniform distribution). The parameter $n$ is unknown. Let $U$ be the number of unique values seen in the sequence. Given $k$ and $U$, how to estimate $n$?

thanks to:

$$E(U) = n\left(1-\left(1- \frac1n\right)^k\right)$$

it "seems a good idea", given a value $u$ and a value $k$ to choose an estimator $\hat n$ of $n$ as the real root $> 1$ of the equation $x\left(1-\left(1- \frac1x\right)^k\right) - u = 0.$

How to turn this "seems a good idea" argument into a real probabilistic/statistic argument, i.e. how to create a rigourously defined estimator (using Estimation theory in Statistics) from this?

Additionally, how could we create a 95% confidence interval from this?

Note: I already read this answer and the article from W. Esty (Ann. Statist., 1983) but this needs extra information like the number of items seens once or twice, which I don't want to use.

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    $\begingroup$ This is basically a method of moments estimator, no? $\endgroup$ Commented Nov 10, 2017 at 17:27
  • $\begingroup$ @tchakravarty can you explain how this would work? $\endgroup$
    – Basj
    Commented Nov 14, 2017 at 12:07

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