Understanding the Impact of Short Term Variance in Trading

Feb 06, 2024

In the world of trading, understanding the impact of variance is essential for making informed trading decisions. Variance, particularly short-term variation, can have a significant influence on trading outcomes, yet it's often overlooked or misunderstood by many traders.

In this blog post, we'll explore the concept of short-term variance in trading, using the analogy of flipping a coin to illustrate its effects. We'll also discuss the pitfalls of relying on short-term data and provide insights into how traders can effectively navigate variance to develop robust trading strategies.

The Coin Flipping Analogy

Imagine flipping a coin 200 times. In the first 100 flips, you might find that you win 65% of the time, while in the next 100 flips, your win rate drops to 35%. Despite these fluctuations, the overall win rate aligns with the expected 50% win rate for a fair coin. This scenario perfectly illustrates the concept of short-term variance in trading. Now imagine those coin flips were trades.

How many of you would get overconfident during the first 100, size up to only take the next 100 and end up down overall, or quit completely? 

Pitfalls of Short-Term Data Analysis

Many traders fall into the trap of analysing short-term data and drawing conclusions based on limited sample sizes. They may backtest a trading strategy using only a handful of trades and mistakenly believe they've discovered a foolproof method for success. However, short-term variance can lead to misleading results, as random fluctuations in market conditions can significantly impact performance over a small number of trades.

The Importance of Long-Term Analysis

To truly understand the effectiveness of a trading strategy, it's essential to analyse data over a more extended period, encompassing a larger sample size of trades. By examining performance over thousands of trades, traders can better assess the consistency and reliability of their strategies, accounting for the effects of short-term variance.

Navigating Variance in Trading

To navigate the challenges of short-term variance, traders should focus on developing robust trading strategies that are resilient to fluctuations in market conditions. This may involve incorporating risk management techniques, such as proper position sizing and diversification, to mitigate the impact of variance on portfolio performance.

The Psychological Aspect of Variance

To help with trading psychology understanding variance plays a pivotal role in maintaining a balanced mentality. By diligently tracking their trading data and analysing performance over time, traders gain valuable insights into their own patterns of success and failure. This self-awareness allows them to adjust their mentality accordingly, whether they're experiencing a hot streak or going through a cold spell. Recognizing that short-term variance is a natural part of the trading journey can help traders avoid emotional highs and lows, enabling them to make rational decisions based on long-term data rather than short-term fluctuations.

Ultimately, mastering the psychological aspect of trading is just as critical as mastering the technical aspects, and understanding variance is a powerful tool for achieving emotional resilience in the face of market volatility.


In conclusion, short-term variance is a fundamental aspect of trading that can significantly influence outcomes. By understanding the limitations of short-term data analysis and emphasizing the importance of long-term analysis, traders can develop more reliable and effective trading strategies. Remember, success in trading requires patience, discipline, and a thorough understanding of the dynamics of variance in the market. So, the next time you're tempted to draw conclusions based on short-term results, take a step back, analyse the bigger picture, and make informed decisions based on a comprehensive evaluation of data.