Expert Advisor Assumptions

Many of our clients are ordering their first custom programming projects. They know the general framework of the expert advisor that they hope to create, but they are not sure of what to ask for specifically. The goal of this post is to outline how an EA functions in relation to the most commonly asked questions.

How do I select the currency pair and time frame that my expert advisor should use for trading?

An Expert Advisor runs on the chart where the user applies it. When you wish to trade an EA on the EURUSD M15 chart, open a EURUSD chart. Change the time frame to M15. Apply the EA. All decisions will be based on the chart.

What are inputs?

Inputs are variables that the user can change without additional programming. Traders often know the indicators that they like using. The settings are often less clear. Inputs allow for tweaking or experimenting without needing to email the programmer every time that you change your mind. A more concrete example is to consider an EA that uses a moving average. Is a 50 period MA better than a 55 period MA? Making the period an input allows the trader to experiment quickly and easily.

How does my EA choose how many lots it should trade?

I assume that you wish to trade fixed lot sizes unless you tell me otherwise. Most of our SOWs include a Lots input. Any trading signals that appear would enter with the amount that you enter for Lots. Clients frequently request other types of money management. You need to explicitly state the type of money management that you wish to include or else it will not be in the expert advisor.

Why does every SOW include a stop and take profit?

Mostly because it does no harm being in there. Setting them to zero will disable each of their functionalities. The vast majority of clients want the ability to select stops and limits. Our programming templates automatically include them to help speed up the development process and to reduce costs for our clients.

What is the difference between a generic trailing stop and a breakeven trailing stop?

A generic trailing stop is what most people think of when the word trailing stop appears. It maintains a set distance from the most favorable price seen. A breakeven trailing stop is more complicated. It was covered in a previous blog post.

What is the purpose of an SOW? Why are you so insistent on pinning down all of the details?

All of our projects are pre-paid. Before we required SOWs for all projects, the expectations between OSR and the client often differed. The customer expected one thing; we expected another. It’s worth taking the extra time to make sure that everyone understands the project and what is expected.

The SOW also allows us to develop a working relationship before any money changes hands. You feel more comfortable with the purchase when you already know that we understand the project from top to bottom.

I want to trade 10 currency pairs at a time. Why can’t a single EA manage all 10 currency pairs?

A single expert advisor technically could manage multiple time frames and multiple currencies. I recognize that the idea is nice; why manage 10 EAs when you could only manage 1 EA? The problem is that MT4 EAs depend on incoming ticks to update. If the expert advisor wants to trade the AUDUSD but it’s applied on the EURUSD, the trade won’t fire off until the EURUSD receives an incoming quote. That’s not good, especially with short time frames. There’s the risk of trades firing off later than expected, trailing stops taking too long to update, etc. More importantly, the execution will always bottleneck because of the trade context is busy error.

I welcome questions on these blog posts. If you’ve always wondered how EAs work and would like your question answered on the blog, then send me an email.