# Percent Change Since Open

This study calculates and displays the Percent Change Since Open of the data specified by the Input Data Input.

Let $$X_t$$ and $$O_t$$ the values of the Input Data and Open Prices, respectively, at Index $$t$$, and let $$v$$ be the Multiplier Input. The Percent Change Since Open at Index $$t$$ is denoted as $$\%\Delta X^{(O)}_t(v)$$, and it is calculated as follows.

$$\displaystyle{\%\Delta X^{(O)}_t(v) = v\cdot\frac{X_t - O_{t_{start}}}{O_{t_{start}}}}$$

$$t_{start}$$ is determined as follows.

• If the Start Time Input is set to Trading Day Start Time, then $$t_{start}$$ is the Index of the first bar of the trading day.
• If the Start Time Input is set to First Bar In Chart, then $$t_{start} = 0$$, which is the Index of the first bar in the chart.

Note: This formula only give a true Percent Change if the Multiplier Input is set to $$100$$.

More detailed information about how the Start Time is determined can be found in the section on Session Times.

#### Inputs

• Start Time: When set to Time Period Type/Length, then the Time Period Type and Time Period Length Inputs set the time period to calculate percent change since open for. This calculation will repeat for each of the periods in the chart starting from the beginning of the chart. The beginning of each time period is affected by the chart Session Times settings.

If this is set to First Bar in Chart, the opening price used for the percentage calculation is the opening of the first bar in the chart and the calculation continues until the last bar in the chart without resetting.

Through Chart >> Chart Settings, you can control the starting date in the chart or how many days to load in the chart to control the opening price when using First Bar in Chart. Refer to Use Date Range >> From / To.
• Time Period Type: Sets the type of time period for the calculation. This Input works in conjunction with Time Period Length. For a 1 Day period, set this to Days. The number of Days specified always refers to calendar days and not trading days.
• Time Period Length: Sets the quantity to be used with Time Period Type. For example, for a period of 1 Day, set this to 1 and set Time Period Type to Days.
• Input Data for Opening Bar: This is the Input Data element of the bar for the bar at the open for the time period.
• Input Data for Current Price: This is the Input Data element of each bar to calculate the price change as compared to the opening bar.
• Multiplier: This multiplies the Percent Change at each bar by the amount specified.

The spreadsheet below contains the formulas for this study in Spreadsheet format. Save this Spreadsheet to the Data Files Folder.

Open it through File >> Open Spreadsheet.

#### Percent Change for Different Symbol

In order to show the Percent Change Since Open on a single chart for multiple symbols, follow these instructions:

1. Create a chartbook with the appropriate symbols displayed in each chart.
2. Select the chart on which the multiple studies will be placed.