Basic information on financial databases: cook books, tips and tricks & economic news

This blog contains schematic easy to grasp - hands on - help in performing searches in economic databases, making work sets and making them inter-exchangeable between the databases.

* Disclaimer. I am not a finance professional. Most posts are the result of personal findings.

All presented images are scaled and can be enlarged to original size (click the picture).

Search This Blog


Datastream: expressions, charting and both

(changed, Dec. 12, 2014)
Datastream offers a wide range of ready made expressions and functions, which can save considerable time compared to doing your own calculations. Think of (standard)Deviation, Moving average, Cumulative sum etc.

Charting Menu
This a a "dirty, but easy" method of finding expressions and functions in Datastream.

Open naviator
In Criteria selection press link Charting 

The charting screen opens

It can happen that the results of another user are presented.
Clear the data with the white leaflet.


If you want to search for items and data, the arrow buttons open new menus.

The principles are similar to the regular search screens.
Comparing a fund with an index might produce a useless chart (equities and indexes are different entities, after all)

Absolute values
Note the Ahold line (blue)
Shown are the default datatypes (price)
There are ways to make this comparison more useful.
Return Index Ri

These are still absolute values... better is to go for relative values/ changes..

changes like moving average.
MAV#(AMSTEOE(RI),1Y) and MAV#(H:AH(RI),1Y) or PCH (percentage change)

Button ƒx calls up a menu

Mouse over:

Note the bottom three options.
USE stored expressions...

After pressing the option the following (large) menu appears:
Note ratios and regression, risk and volatility

Sticking to Return Index and Moving Average, filterings result in
(note search term in top bar)


Moving average

Historical Beta

As you can see searching for expressions like betas and such with this menu is not complicated.
All presented expressions and formulas can be copied and used in another Datastream menu.
When you're not interested in a chart but in figures, another option is to use the 
Datastream Menu (Expression picker/ builder)

From the Datastream menu press:

The result looks familiar. But pay attention to the 2nd TAB.

When this is too hard core, there is the same ƒx button available on the menu screen:

Moving average:

Looking up Expressions in the Extranet:
Mentioned are:
Percentage change
Historical Beta
Moving average
Annualised volatility

Also look up info in these posts:

A couple of terms
Volatility refers to the amount of uncertainty or risk about the size of changes in a security's value. High volatility means that the price of the security can change dramatically over a short time period in either direction.

A statistical measure of the dispersion of returns for a given security or market index. Volatility can either be measured by using the standard deviation or variance between returns from that same security or market index. Commonly, the higher the volatility, the riskier the security.
Historical Volatility
The realized volatility of a financial instrument over a given time period. Generally, this measure is calculated by determining the average deviation from the average price of a financial instrument in the given time period. Standard deviation is the most common but not the only way to calculate historical volatility.

Implied volatility
In addition to known factors such as market price, interest rate, expiration date, and strike price, implied volatility is used in calculating an option's premium. IV can be derived from a model such as the Black-Scholes Model.

The estimated volatility of a security's price. In general, implied volatility increases when the market is bearish and decreases when the market is bullish. This is due to the common belief that bearish markets are more risky than bullish markets.

Believing that a particular security, a sector, or the overall market is about to fall.

Believing that a particular security, a sector, or the overall market is about to rise.

(Sources Investopedia and


No comments:

Post a Comment