<p>Indices are typically aggregated to a lower frequency by taking the average over the sub-periods (the 12 months of the year in your case) if it's just to represent the data in that lower frequency.</p>
<p>However, if it's for further analysis, more custom aggregations might be more appropriate and would very much depend on the exact purpose. For example, if you were looking at the impact on inflation, which, let's assume, materialises with a lag of six months, you may want to check whether the average over 1998M7-1999M6 would be a better choice. Or, for example, if it's about the impact of supply chain security, you may want to take the standard deviation over a year or some related measure.</p>

CC BY-SA 4.0
2022-08-18T08:17:46.137Z
2022-08-18T11:58:40.023Z
2022-08-18T11:58:40.023Z
BrsG
<p>From <a href="https://libertystreeteconomics.newyorkfed.org/2022/05/global-supply-chain-pressure-index-may-2022-update/" rel="nofollow noreferrer">(Benigno, 2022)</a> I have an index called Global Supply Chain Pressure Index (GSCPI) provided at the end of the post. The index was shared at monthly frequency.</p>
<p>A part of the data provided is as below</p>
<p><a href="https://i.sstatic.net/OZBTe.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/OZBTe.png" alt="enter image description here" /></a></p>
<p>Now I want the annual data, for example, the GSCPI of year 1998 and 1999. Could you please tell me what I should do in such a case?</p>

CC BY-SA 4.0
2022-08-18T07:02:06.877Z
Seems the index is normalized such that a zero indicates that the index is at its average value with positive (negative) valued representing how many standard deviations the index is above (below) this average value. Insofar, I am not sure how one would interpret an annual value (ie.g. it's not a flow). What would you need this for?
Alex
CC BY-SA 4.0
2022-08-18T07:03:50.160Z
@Alex because other variables are at annual frequency
Phil Nguyen
CC BY-SA 4.0
2022-08-18T07:05:22.410Z
If it's just end of year GDP or the like, I think it's valid to just use and of year (DEC) of the index. It literally just shows the SD from average (at any point in time that is reported).
Alex
CC BY-SA 4.0
2022-08-18T07:22:25.153Z
@Alex , so you mean the index GSCPI for 1998 is **-0.56** and 1999 is **-0.02** if I understand you correctly?
Phil Nguyen
CC BY-SA 4.0
2022-08-18T07:46:41.450Z
@PhilNguyen: for what purpose do you need the annual aggregation?
BrsG
CC BY-SA 4.0
2022-08-18T08:00:32.083Z
@BrsG to align with other variables in the regression. All other variables are at annual levels.
Phil Nguyen
CC BY-SA 4.0
2022-08-18T08:03:10.717Z
To align for what purpose? Further analysis, or just to represent the data in the same frequency?
BrsG
CC BY-SA 4.0
2022-08-18T08:06:07.217Z
@BrsG to run the regression. To run the regression, all variables should have the same frequency. For example, all variables have annual frequency
Phil Nguyen
<international-economics><data>
How to have the yearly index when having monthly index?
Phil Nguyen
# How to have the yearly index when having monthly index?

(Asked by: username_0 on 2022-08-17)

From [(Benigno, 2022)](https://libertystreeteconomics.newyorkfed.org/2022/05/global-supply-chain-pressure-index-may-2022-update/) I have an index called Global Supply Chain Pressure Index (GSCPI) provided at the end of the post. The index was shared at monthly frequency.

A part of the data provided is as below

[![enter image description here](https://i.sstatic.net/OZBTe.png)](https://i.sstatic.net/OZBTe.png)

Now I want the annual data, for example, the GSCPI of year 1998 and 1999. Could you please tell me what I should do in such a case?

**Tags:** international-economics, data

> **Comments:**
> **username_1**: Seems the index is normalized such that a zero indicates that the index is at its average value with positive (negative) valued representing how many standard deviations the index is above (below) this average value. Insofar, I am not sure how one would interpret an annual value (ie.g. it's not a flow). What would you need this for?  
> **username_0**: @username_1 because other variables are at annual frequency  
> **username_1**: If it's just end of year GDP or the like, I think it's valid to just use and of year (DEC) of the index. It literally just shows the SD from average (at any point in time that is reported).  
> **username_0**: @username_1 , so you mean the index GSCPI for 1998 is **-0.56** and 1999 is **-0.02** if I understand you correctly?  
> **username_2**: @PhilNguyen: for what purpose do you need the annual aggregation?  
> **username_0**: @username_2 to align with other variables in the regression. All other variables are at annual levels.  
> **username_2**: To align for what purpose? Further analysis, or just to represent the data in the same frequency?  
> **username_0**: @username_2 to run the regression. To run the regression, all variables should have the same frequency. For example, all variables have annual frequency  

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## 1 answers

### Answer by username_2 on 2022-08-18. Score: 1

Indices are typically aggregated to a lower frequency by taking the average over the sub-periods (the 12 months of the year in your case) if it's just to represent the data in that lower frequency.

However, if it's for further analysis, more custom aggregations might be more appropriate and would very much depend on the exact purpose. For example, if you were looking at the impact on inflation, which, let's assume, materialises with a lag of six months, you may want to check whether the average over 1998M7-1999M6 would be a better choice. Or, for example, if it's about the impact of supply chain security, you may want to take the standard deviation over a year or some related measure.


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