Excel

 Хичээл https://www.excel-easy.com/examples/forecast.html 

2. Enter the value 89 into cell C11, select the range A1:C14 and insert a scatter plot with straight lines and markers. The FORECAST.ETS function in Excel 2016 or later is a great function which can detect a seasonal pattern. 1. The FORECAST.ETS function below predicts a future value using Exponential Triple Smoothing.

FORECAST.LINEAR 1. The FORECAST.LINEAR function below predicts a future value along a linear trend.

 Explanation: when we drag the FORECAST.LINEAR function down, the absolute references ($B$2:$B$11 and $A$2:$A$11) stay the same, while the relative reference (A12) changes to A13 and A14.

The FORECAST (or FORECAST.LINEAR) function in Excel predicts a future value along a linear trend. The FORECAST.ETS function in Excel predicts a future value using Exponential Triple Smoothing, which takes into account seasonality.

Note: the FORECAST function is an old function. Microsoft Excel recommends using the new FORECAST.LINEAR function which produces the exact same result.

FORECAST.LINEAR

1. The FORECAST.LINEAR function below predicts a future value along a linear trend.

Explanation: when we drag the FORECAST.LINEAR function down, the absolute references ($B$2:$B$11 and $A$2:$A$11) stay the same, while the relative reference (A12) changes to A13 and A14.

2. Enter the value 89 into cell C11, select the range A1:C14 and insert a scatter plot with straight lines and markers.

Note: when you add a trendline to an Excel chart, Excel can display the equation in a chart. This equation predicts the same future values.

The FORECAST.ETS function in Excel 2016 or later is a great function which can detect a seasonal pattern. 1. The FORECAST.ETS function below predicts a future value using Exponential Triple Smoothing.

Note: the last 3 arguments are optional. The fourth argument indicates the length of the seasonal pattern. The default value of 1 indicates seasonality is detected automatically. 2. Enter the value 49 into cell C13, select the range A1:C17 and insert a scatter plot with straight lines and markers.

3. You can use the FORECAST.ETS.SEASONALITY function to find the length of the seasonal pattern. After seeing the chart, you probably already know the answer. Conclusion: in this example, when using the FORECAST.ETS function, you can also use the value 4 for the fourth argument.