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Jul 27, 2023 at 2:27 comment added profPlum @WavesWashSands how did you get that: 𝑉𝑎𝑟(𝛽̂)=𝑉𝑎𝑟((𝐗^𝑇𝐗)^{−1}𝐗^𝑇𝐘)=(𝐗^𝑇𝐗)^{−1}𝐗^𝑇𝑉𝑎𝑟(𝑌)𝐗(𝐗^𝑇𝐗)^{−1} This could be a stupid question but I'm not sure what identities you used here?
Jan 23, 2023 at 16:45 comment added Julien Does thoses first formulas hold for logisitic regression? (The ones until $Var(\pmb{\hat{\beta}}) = \sigma^2(\mathbf{X}^T \mathbf{X})^{-1}$)
Jun 9, 2021 at 20:37 comment added Brian In response to one of the comments, the reason for "The response vector 𝐘 is multivariate normal, so 𝛽̂ is normal as well" is that $\beta$ is a linear function of Y. A linear transformation of a normal distribution is also normal.
Dec 11, 2020 at 12:00 comment added JRC Good explanation @WavesWashSands !
Oct 5, 2019 at 0:17 comment added WavesWashSands @curious_dan Beta hat (not beta, I suppose it's a SE formatting issue) is a linear function on a multivariate normal vector.
Oct 3, 2019 at 18:08 comment added curious_dan Can someone provide justification for this part of the proof: "The response vector 𝐘 is multivariate normal, so 𝛽̂ is normal as well" ?
Jun 18, 2017 at 14:06 vote accept Pieter Verschaffelt
Jun 18, 2017 at 14:06 comment added Pieter Verschaffelt I did indeed use the wrong X. Thank you for the very good explanation and clarification. I do understand what's happening now :)
Jun 18, 2017 at 13:50 history edited WavesWashSands CC BY-SA 3.0
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Jun 18, 2017 at 13:41 history answered WavesWashSands CC BY-SA 3.0