It's popular in the #NoEstimates community to claim *Forecasting* is not *E**stimating*. Using English Dictionaries, they build a case using logical like this. It's been repeating nearly continuously since the start of the discussion about how to make decisions in the presence of uncertanty without estimating.

Salviati:

If you have a number of uniform sized tasks & know velocity you can predict ttc (Time to Complete)Simplicio responds:Indeed...gives us much stronger forecasting ability than estimation

Let's use the Oxford Dictionary of Mathematics, not the High School English Dictionary.

It ain't so much the things we don't know that gets us in trouble. It's the things we know that ain't so - Artemus Ward

**Estimate**

- Point Estimate - A single value of a statistic derived from a sample that is taken as an approximation for the population value of that statistic. For example, the sample mean , x , is a point estimate of the population mean, μ
- Interval Estimate - An inference made about the range of values within which a population parameter will lie, drawn from values obtained from a random sample.
- Interval Estimate - An interval within which a parameter under study (such as a relative risk ) is stated to lie with a particular degree of confidence, likelihood, or probability based on an analysis of a study or multiple studies. See also confidence interval.
- Maximum Likelihood Estimate - The value for an unknown parameter in a model that maximizes the probability of obtaining exactly the data that were observed.
- Estimation is used to calculate an unknown value.
- Estimation is the calculated approximation of a result.

**Forecast**

- Forecast - Also referred to as prediction. In econometrics, a point forecast is the expected value of the variable of interest, or the dependent variable, conditional on the given values of the exogenous and predetermined variables. An interval forecast is the confidence interval for the point forecast.
- Forecast - To predict or estimate a future event or trend.
- Forecast - A statistical synthesis of probabilities and expert opinion that attempts to define an outcome either in terms of numbers or actual courses of action.
- Sale Forecast - An estimate of future sales volumes and revenue. It is usually based on past trends and takes into account current and future directions.
- Forecasting - prediction of future events.
- Forecasting is the process of making a forecast or prediction. The terms forecast and prediction are often used interchangeably but sometimes forecasts are distinguished from predictions in that forecasts often provide explanations of the pathways to an outcome.
- Forecasting - to calculate or predict (some future event or condition) usually as a result of study and analysis of available pertinent data predict.

Estimating is about the past, present, and future outcomes of a process, a model, or some external observation. We can estimate the number leaves that have fallen and need to be raked come fall, to size how many bags have to be bought at Home Depot (past). We need to estimate the number of people on the Pearl Street Mall right now to assess how long the walk will be to Starbucks from our parking spot (present). We can estimate the number of minutes we'll need to reach our favorite parking spot at Denver International Airport from the office parking lot (future).

Forecasting is Estimating about the future. The weather forecast for tomorrow is 70 degrees and a 30% chance of rain in northern Boulder County (where we live). With this forecast, we can estimate what time we need to tee off to have a high probability of getting all 18 holes of golf on our course in before the rain starts.

Forecasting is estimating about the future