Talk:Modified Dietz method

Alternative calculation
In the calculation of the Weight in the denominator of the modified Deitz method would it be okay to suggest an alternate calculation something like

Wi = (End Date - Date of flow)/(End Date - Initial investment Date)

If you take the value of CD (Calendar Days) = End Date - Initial Investment (or maybe Begin Investment) Date and Di = Date Flow occurs - Initial investment Date.

I was trying to put this into an excel spreadsheet and found I was calculating based on the dates to get the Calendar Days. — Preceding unsigned comment added by Dhenne (talk • contribs) 18:58, 23 March 2013 (UTC)


 * You are nearly right, but just be careful about the length in days of a period between two dates, which is end date minus start date plus 1.Jonathan G. G. Lewis 19:11, 1 April 2013 (UTC) — Preceding unsigned comment added by Jonazo (talk • contribs)


 * My previous comment assumes you take the start date of the period to be the day after the end date of the previous period. If you take the start date of the current period to coincide with end date of the previous period, then the contributor's formula (above) works just fine. --Jonathan G. G. Lewis 01:50, 4 January 2016 (UTC)


 * Just to add one final point: the contributor's formula assumes the flow is at the same time of day as valuations, i.e. end-of-day, if you are using closing prices and valuations.--Jonathan G. G. Lewis 01:53, 4 January 2016 (UTC)

Do you know that what The Dietz Method means in chinese?THANKS!
In response to this query posted anonymously, although I learned a little Chinese 20 years ago, I have never come across any reference to the Dietz method in Chinese. Sorry. Can anyone else help? Jonathan G. G. Lewis 08:44, 22 November 2013 (UTC) — Preceding unsigned comment added by Jonazo (talk • contribs)

Substantial re-write of this page
I have substantially re-written this page.Jonathan G. G. Lewis 18:08, 29 March 2012 (UTC) — Preceding unsigned comment added by Jonazo (talk • contribs)

Removal of Proposal for Deletion
There was a proposal for deletion added to this page. I removed it because the article is very useful to people in the portfolio management fields who otherwise would need to wade through archaic academic texts to get the same information. This methodology is still in use today. The Global Investment Performance Standards (GIPS) recommends this methodology to standardize return calculations across the industry.

Investopedia reference to Mod Dietz method GIPS Standards Bigbadman (talk) 21:37, 13 January 2015 (UTC)

Thanks for removing the proposal for deletion. Improvements to the article to comply with Wikipedia standards and thereby help to keep it safe from deletion are also very constructive and appreciated. This is a basic and significant topic in the field of investment performance measurement. Jonathan G. G. Lewis 17:28, 23 January 2015 (UTC) — Preceding unsigned comment added by Jonazo (talk • contribs)

Accusation of Breach of Copyright
I was astonished to notice that content I composed and had added to the article had subsequently been removed, some time ago, with a justification that it was in breach of someone else's copyright. The fact is that the content on this page was written entirely independently, off the top of my head. No matter! Jonathan G. G. Lewis 15:52, 3 March 2015 (UTC) — Preceding unsigned comment added by Jonazo (talk • contribs)

New Section: Adjustments
After encountering confusion over the application of the modified Dietz method when a portfolio is empty either at the beginning or end, I decided this new section was required.

--Jonathan G. G. Lewis 00:52, 26 November 2016 (UTC) — Preceding unsigned comment added by Jonazo (talk • contribs)

I just added a new subsection on contributions and weights.

--Jonathan G. G. Lewis 12:26, 13 January 2017 (UTC) — Preceding unsigned comment added by Jonazo (talk • contribs)

Annualized and unannualized
An editor added a line claiming that the calculation of unannualized IRR was incorrect. IRR is normally an annualized rate of return. The example in this article was a comparison between the IRR method and the Modified Dietz method over a holding period of two years. Modified Dietz is a method to calculated the unannualized holding period return. The formula applied for the equivalent IRR is likewise unannualized, and treats the whole two year period as a single unit. --Jonathan G. G. Lewis 02:08, 10 November 2021 (UTC)