Forecasting challenges with auto-checking and feedback
Forecasting Challenges
Apply your trend line interpretation skills to new scenarios with auto-checking
Test your ability to calculate predictions from trend lines. Use the pattern to forecast the answer.
1. A trend line shows café sales increasing by $350 per month. If January sales were $8,000, what would you predict for April?
2. A scatter plot shows a negative relationship between temperature and hot chocolate sales. What does this mean?
3. A trend line has R-squared = 0.85. What does this tell you about predictions?
4. Sarah uses 6 months of data to predict 5 years into the future. Why is this problematic?
5. A trend line shows that for every $1 spent on advertising, café sales increase by $2.50. What is the slope in this context?
6. The trend line goes up steeply. What does a steep slope tell you?
Read each scenario and identify what the pattern suggests. Focus on the relationship shape and what it implies.
Scenario 1: Based on this pattern, predict Month 6 sales.
A café tracks weekend sales and finds: Month 1: $9,200, Month 2: $9,600, Month 3: $10,000, Month 4: $10,400
Hint: The pattern shows $400 increase per month. Month 6 is 5 months after Month 1.
Scenario 2: What is happening to the relationship as staff increases beyond 4?
A restaurant finds that when they have 4 staff members, sales are $5,200. With 5 staff, sales are $5,600. With 6 staff, sales are $5,900.
Hint: 4→5 adds $400, 5→6 adds $300. The additional benefit is shrinking.
Scenario 3: What would you predict for a very hot day (95°F)?
A coffee shop's data shows a strong positive relationship between morning temperature and iced coffee sales.
Hint: Positive relationship means both increase together. Very hot = very high predicted sales.
Discussion: What patterns do you notice?
- How did you calculate the Month 6 prediction?
- What does "diminishing returns" mean for business planning?
- Why is it important to think about the relationship shape, not just the final number?
Good analysts know the limits of their models. Here's where forecasting breaks down.
Danger Signs
- Low R-squared - pattern is weak
- Predicting far outside data range
- Major changes in business conditions
- New competitors or regulations
- Single unusual event in the data
What To Do Instead
- Use ranges, not single numbers
- Build in safety margins
- Plan for multiple scenarios
- Update predictions frequently
- Combine with expert judgment
Common Forecasting Mistakes
False precision: "Sales will be exactly $9,847" - instead say "likely between $9,000-$10,500"
Ignoring uncertainty: Treating the prediction as a guarantee rather than a reasonable estimate
Extrapolation abuse: Using a short trend to predict far into the future
Assuming no change: "The pattern will continue exactly" when conditions may change
Before moving to the assessment, check that you can do each of these:
Conceptual Understanding
- ✓I can explain what a trend line shows and what it doesn't promise
- ✓I can distinguish between positive and negative relationships
- ✓I understand what R-squared means (consistency, not quality)
- ✓I know when predictions become unreliable
Applied Skills
- ✓I can calculate a simple prediction from slope and starting value
- ✓I can interpret what the slope means in business terms
- ✓I can identify diminishing returns patterns
- ✓I can explain why forecasting has limits
Mastery Target
If you can check all 8 items, you're ready for the assessment. If you have gaps, review the relevant phase before continuing.