Timeline for Does transpose commute through expectation?
Current License: CC BY-SA 3.0
3 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jan 10, 2012 at 18:39 | comment | added | whuber♦ | Looking at the simplest non-trivial example can help. For instance, when $\mathbf{x}$ is a row vector of length 2, say with components $x_1$ and $x_2$, then $\mathbf{x}^t$ is a column vector of length 2 with components $x_1$ and $x_2$. The expectations are $E[x_1]$ and $E[x_2]$: these are the components of $E[\mathbf{x}]$ and $E[\mathbf{x}^t]$; the only difference is that in the first case they are arranged side-by-side in the row vector and in the second they are arranged top-to-bottom in the column vector. | |
| Jan 10, 2012 at 18:21 | comment | added | Swiss Army Man | Thanks, can you give me a direction for the long answer or a reference? I'm very curious about the fundamental reason. | |
| Jan 10, 2012 at 17:38 | history | answered | jbowman | CC BY-SA 3.0 |