Return Time Analysis
Description
This tool calculates the probability that a specific event or critical value will occur again over a specified number of years.
Discussion of the Output Data
The output consists of the the return interval, the probability in any given year, and numerical and graphical output of the recurrence probabilities from year one to year N (where N is the value entered for "Years to Compute Probability" under "Analysis Input" below). The title of the graph is the same title as specified in the "Output File Header" below.
Input
Input File
Select the input data by clicking on "Browse" and navigating to the proper file.
Input Data Format
Year / Data
Each "/" is a tab (i.e., data should be tab-delimited). Missing Data should be denoted as "-99".
Start Row
This input is the row number where the data to be processed begin in the input file selected above. An example of how row numbers are entered is shown in Figure 2 located in the Running HOB Tools topic.
Data Column Number
This input is the column number where the data are located in the input file selected above. An example of how column numbers are entered is shown in Figure 2 located in the Running HOB Tools topic.
Analysis Input
Year to Start Analysis
Enter the year when the return time analysis should start.
Year to End Analysis
Enter the year when the return time analysis should end.
Critical Value
Enter the critical value that will be used to compute the recurrence probabilities. Note that the proper symbol needs to be selected in order to calculate the correct probability (i.e., >= for greater than or equal to, <= for less than or equal to). Thus, to determine recurrence probabilities for low values, select "<=" and then enter the critical value. Select ">=" and then enter the critical value to calculate recurrence probabilities for high values.
Years to Compute Probability
HOB Tools will compute the probability that the critical value will be met or exceeded for each year from one to the value entered in this box. The default value is 100. If left unchanged, then the numeric and graphical output will contain recurrence probabilities from year 1 to year 100.
Output
Output File
Select the file where the numerical results will be stored.
Output File Header
Information entered here will be output in the first line of the output file.