What you will learn
- Spread changes
- Quiet periods and thin books
- Open and close behavior
- Why averages do not guarantee today's conditions
Spread changes
Spread is an observable execution cost that can vary across a session. Compare the relevant quote side and size. A historically narrow spread is a reference, not a promise of the next fill.
Quiet periods and thin books
Quiet periods may have fewer participants or less displayed quantity. Thin liquidity can increase the impact of an order or a sudden headline. Low recent volatility does not guarantee low execution risk.
Open and close behavior
Open and close behavior depends on venue mechanisms, order imbalances and information arriving since the preceding session. A pattern around one venue's open may not transfer to another feed's arbitrary daily boundary.
Why averages do not guarantee today's conditions
An average hides variation. A session's typical spread or movement should be accompanied by a range or distribution and a sample definition. Planning exclusively around the mean can ignore the conditions that cause the largest execution problems.
Worked example
A sample has nine observations of spread 1 and one of spread 11. The mean is 2, but a plan assuming every observation costs 2 misses both the common condition and the outlier.
Try it yourself
Calculate the median and mean of that sample and explain why neither alone specifies the cost of the next order.
Show the worked solution
The median is 1 and mean is 2. They summarize the sample differently; neither predicts a guaranteed next observation. The outlier and the conditions producing it remain relevant to planning.
Apply this to your course project
Build a timezone-correct weekly schedule with holiday and event checks.
Keep the calculation inputs, assumptions and decisions with your work. Practical exercises are self-reviewed; the scored knowledge checks assess the questions shown, not an independent certification of practical competence.