> For the complete documentation index, see [llms.txt](https://docs.geodin.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.geodin.com/data-analysis/regression-and-curve-fitting.md). # Regression and Curve Fitting This page is the reference for the time-series and measurement-value series properties used in regression and curve-fitting work: the series **presentation options** (curve, bar, symbol and table drawing), the measurement-editor **toolbar functions**, the **Ion balance** calculation, and the **regression calculation** branch of a time-series element. Each section below describes one property branch or method; choose a subordinate branch to edit its detail properties. *** ## Reference: Series presentation ### Presentation options Optionally in a time line series presentation curves, bars and symbols (in any combination) can be used. If no presentation type is chosen, the series is not displayed (this can be sensible for series, which are used for aggregations). By default, two measuring points are connected by a line in the graph, which is inclined differently at each measurement values. With the option <**Step plot**> presentations can be achieved, which show a measuring point **from** a certain time. For the following measurement, the curve is drawn as a horizontal line and then perpendicularly to the next value. With this type of representation, the option <**drawing till end of diagram**> can be helpful, which continues the line of the series until the end of the timeline. Thus it can be shown that the measured value has not changed since the last measurement By default data records on a curve are ignored if the chosen parameter has no value (although a time exists) and a line is drawn through these records. This line can be interupted using the option **break line for empty records**. For the presentation type <**Bar chart**> the bar width can be selected. Like for the presentation type <**Symbols**>, here you can select, whether this should be drawn in the areas, in which samples were only taken seldomly (i.e. for interruptions of the curve). ### Curve In this branch no properties can be selected. Choose a subordinate branch, to edit detail properties. ### Line Additionally to presenting the series in a curve, bar or symbol any number of calculated (horizontal) lines can be added to a series. Here three statistic parameters **Minimum**, **Mean value**, **Maximum** and **Median** are available, which are calculated basing on measurement values. Additionally numeric values of the Object data can be displayed. The selection is done in the drop down menu **"Calculation type"**. By selecting the type Object data in the underlying input field the data field can be chosen, which contains the numeric value. By choosing the statistic parameters you select, whether here only the **Values of the displayed time interval** or **All measurement values** of the measurement point (not depending on the time interval displayed in the diagram) should be used. A line or outline is displayed in the chosen Color and Line type. To select a color, which is not available in the drop down menu, click in the list on the first entry **"Individually"**. In the color dialogue you can adjust a new color. The line thickness can be chosen in mm or pixels. The selection should be done in mm by preference. In this case the thickness of the lines in the preview is not equal to the print output and not depending on the used print resolution. The selection of a line thickness in pixels is only suitable for graphs, which are only viewed on the screen. ### Drawing type Selection of the presentation in graphic (Curve, Bar chart, Symbols and Curve + Symbols) or tabular form (Table) of the single measurement values. The presentation type **Curve** starts with the first and ends with the last measured value. The nodes of the curve characterize a measurement point (measurement value in a certain depth). Using the presentation type **Bar chart** the values characterize a measurement sector (interval), so that the first value is valid for the section from 0,00m to the first measurement value. ### bar / curve The option -Close line to axis- is illustrated in the following graph. In the left hand graph the option is deactivated, the surrounding line of the bar graph is not connected with the 0-axis at the starting and ending point. The presentation of a curve can optionally be interrupted in not investigated areas. Here a value for the sector length, from which the area is not investigated, is necessary. A general adjusting possibility of this option for all series is available in the **Presentation options**. The possibility to colorize the view using a diagram as legend is described in detail in the chapter **color coding**. ### Table The tabular presentation of a single measurement value as a text in a certain depth is possible as a combination with a curve or a bar chart and also as a pure table. For this choose the option **-Show individual values-**. Is the option -Show values = 0- deactivated, all individual values that equal zero are counted as fault values and not labeled, otherwise these values are also displayed. The option -Interpret values < 0- causes a presentation of the measurement values after the following rules: Measurement value > 0 Value is labeled normally Measurement value < 0 (except -88 und -99) Labeled as \ uses the GeoDin short parameter names for the table columns in Excel (note for the SDM the column names are identical; the default setting is no/unchecked) <**Name tables after measurement points**> default setting is yes/checked - activating this option names each table tab after the measurement point. ## Reference: Ion balance ### Calculation of the ion balance The following parameters are used to calculate the ion balance: | N | Parameter | P | Type | Factor | Sum | | -- | ------------------ | ----- | ------ | ------ | ------------------------------------------------ | | 1 | Calcium (CA) | **1** | cation | 0,0499 | Total mineralization | | 2 | Magnesium (Mg) | **1** | cation | 0,0822 | | | 3 | Sodium (Na) | **1** | cation | 0,0435 | | | 4 | Potassium (K) | **1** | cation | 0,0256 | | | 5 | Bicarbonate (HCO3) | **1** | anion | 0,0164 | | | 6 | Carbonate (CO3) | **3** | anion | 0,0333 | | | 7 | Chloride (CL) | **1** | anion | 0,0282 | | | 8 | Sulfate (SO4) | **1** | anion | 0,0208 | | | 9 | Iron (total) | **2** | anion | 0,0537 | | | 10 | Manganese | **2** | anion | 0,0364 | | | 11 | Ammonia (NH4) | **2** | anion | 0,0554 | | | 12 | Nitrate (NO3) | **2** | anion | 0,0161 | | | 13 | Nitrite (NO2) | **2** | anion | 0,0217 | | | 14 | Phosphate | **2** | anion | 0,0316 | | | 15 | pH-value | **3** | | | Proton concentration | | 16 | m-value | **3** | | | The parameter is used for carbonate substitution | | 17 | p-value | **3** | | | | | 18 | Carbonate hardness | **3** | | | | | 19 | Total hardness | **3** | | | Total hardness - Check | P = Priority (**1** Main component, **2** secondary component, **3** Substitution)\ N = internal number **Further details:** 1. If iron (total) is not measured, but iron 3, then iron 3 is used 2. If iron (total) and iron 3 are not measured, but iron 2, the iron 2 is used 3. If ammonium is not analyzed, but ammonium N, then is factorized and used 4. If nitrate is not analyzed, but nitrate N, then is factorized and used 5. If nitrite is not analyzed, but nitrite N, then is factorized and used 6. If phosphate is not analyzed, but phosphate P, then is factorized and used ### Preparing the calculation Seven main components and six secondary components are used in the calculation. Before calculation the process is checked with the available data. Values that lie below the detection limit or for which the detection limit is unknown (values -66, -88 or -99) have the value zero for the calculation. For parameters below known detection limits these limits are used in the calculation. The calculation is not carried out when less than five main components are present. If five are present the missing values are estimated for balancing the ionic relationships. By definition only one anion or cation can be missing. For the case that bicarbonate or CO3 were not analyzed, GeoDin tries to use the m-value, p-value and / or carbonate hardness instead. The total hardness check gives the plausibility of the Calcium, Magnesium and Total hardness to each other. The sum of the anions and cations for the error calculation is computed.\ The sum of the cations is added to the proton concentration (calculated from pH). The error is the difference between anions and cations in relationship to the half of the total mineralization multiplied by the sum of the anions and cations. Error = cations - anions / 0.5 \* ( cations + anions) By values less than 5 mmoleq for the total mineralization the ion balance is plausible, if the absolute error is less than 0.05.\ By values more than 5 mmoleq for the total mineralization the ion balance is plausible, if the absolute error is less than 0.02. ## Reference: Regression and curve fitting ### Curve type Here you can select the way the displayed points are connected. For curves, the curve quality can be set. This value determines how many interpolated points are calculated. This value has a considerable influence on the duration of the calculations. ### Regression calculation With the help of a regression calculation you aim to find a relationship between a response (dependent) variable and possible predictor(s) (independent) variable(s) by the method of least squares. A regression calculation allows us to explore the relationship between two (or more) variables. It indicates the nature of the relationship between two (or more) variables. In particular, it indicates the extent to which you can predict some variables by knowing others, or the extent to which some are associated with others. The conditional expected value is referred to here as the **estimation target**. This can be estimated from various ![influencing factors](/files/BkyMvgxn74RTDyPKkEjE) **influencing factors**. **Methodology:** A set of linear equations is constructed using the estimation target and influencing factots. Internally a multiple linear regression calculation is performed which is a method for predicting (approximating) the value of a dependent variable ***y***, based on the value of independent variable(s) ***x***. In a cause and effect relationship, the independent variable is the cause, and the dependent variable is the effect. In our terminology the **influencing factors** are the independent variables ***xi*** and the **estimation target** the dependent variable ***y***. Numerical instability that occur will be recognised during calculation and can be labelled in the status information using the property "IsSingular". If "IsSingular"=True the regression equation or the regression coefficient should not be used and no results will be displayed in the time series graphic. **Considering time as an influencing factor** Set this option if you wish to use time as an influencing factor. The time-stamp of the measurements is interpreted as a numerical value and used for the regression analysis just like one of the the other influencing factors. This option should be used when time dependent relationships between the measurement size exist. ### Input magnitude Please select a measurement size from an existing time series element. This will be considered as a dependent variable y, which is the target of the the regression approximation. ### Effective size **Series** Choose the independent variable source which will be used in the regression calculation as an influencing factor, **Time offset** For the regression calculation it is necessary to analyse the time of each measurement for the source series. Each influencing factor can include a time offset in order to smooth out irregularities in measurement intervals. A time offset of zeo days is only possible in the regression analysis for measurement values taken oin the same day. ### Result text You can position the results of the regression analysis here as freely positionable text. **Statisical results** Choose the statistical result to display from the items in the drop-down list **X, Y** Define the relative position of the text. **Remove text outside the diagram area** The text generated may have large variations in length. This can be truncated when this option is set. ### Event Events generated by a time-series graphic using a regression analysis, are not evaluated directly but may be analysed using the following options. A graphic with a time series element including a regression series can generate events that can be further processed using the "Evaluate measured values" method. With this method, measured values can be automatically subjected to a regression analysis in order to subsequently generate corresponding evaluations for a measured value. **Target field** Choose the field in which a text will be entered upon the event occuring. **Field value** Enter the text to be written to the target field. **Trigger** Choose between the following options: 1. limit exceeded 2. below limit 3. above or below limits 4. within limits ## Related topics * CPT and data-sequence topics: [Data Sequences and CPT](/workspace-and-data-management/working-with-measurement-data/data-sequences-and-cpt.md) * Shared measurement/data-type reference content now lives in [Formulas in Measurement Values](/data-analysis/formulas-in-measurement-values.md) * Shared measurement/data-type reference content now lives in the measurement-data editor reference ([Working with Measurement Data](/workspace-and-data-management/working-with-measurement-data.md)) --- # Agent Instructions This documentation is published with GitBook. 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