Add trendline excel как
These days when technologies, markets and customer needs are changing so rapidly, it is critical that you move with trends, and not against them. Trend analysis can help you identify underlying patterns in the past and current data movements and project future behavior.
Excel TREND function
The Excel TREND function is used to calculate a linear trend line through a given set of dependent y-values and, optionally, a set of independent x-values and return values along the trend line.
Additionally, the TREND function can extend the trendline into the future to project dependent y-values for a set of new x-values.
The syntax of the Excel TREND function is as follows:
Known_y's (required) - a set of the dependent y-values that you already know.
Known_x's (optional) - one or more sets of the independent x-values.
- If only one x variable is used, known_y's and known_x's can be ranges of any shape but equal dimension.
- If several x variables are used, known_y's must be a vector (one column or one row).
- If omitted, known_x's is assumed to be the array of serial numbers .
New_x's (optional) - one or more sets of new x-values for which you want to calculate the trend.
- It must have the same number of columns or rows as known_x's.
- If omitted, it is assumed to be equal to known_x's.
Const (optional) - a logical value specifying how the constant a in the equation y = bx + a should be calculated.
- If TRUE or omitted, the constant a is calculated normally.
- If FALSE, the constant a is forced to 0, and the b-values are adjusted to fit the equation y = bx.
How TREND function calculates linear trendline
The Excel TREND Function finds the line that best fits your data by using the least squares method. The equation for the line is as follows.
For one range of x values:
y = bx + a
For multiple ranges of x values:
- y - the dependent variable you are trying to calculate.
- x - the independent variable you are using to calculate y.
- a - the intercept (indicates where the line intersects the y-axis and is equal to the value of y when x is 0).
- b - the slope (indicates the steepness of the line).
This classic equation for the line of best fit is also used by the LINEST function and linear regression analysis.
TREND function as an array formula
To return multiple new y-values, the TREND function should be entered as an array formula. For this, select all the cells where you want the results to appear, type the formula and press Ctrl + Shift + Enter to complete it. As you do this, the formula will get enclosed in , which is a visual indication of an array formula. Since the new values are returned as an array, you won't be able to edit or delete them individually.
Excel TREND formula examples
At first sight, the syntax of the TREND function might seem excessively complicated, but the following examples will make things a lot easier.
TREND formula for time series trend analysis in Excel
Supposing you are analyzing some data for a sequential period of time and you want to spot a trend or pattern.
In this example, we have the month numbers (independent x-values) in A2:A13 and sales numbers (dependent y-values) in B2:B13. Based on this data, we want to determine the overall trend in the time series ignoring hills and valleys.
To have it done, select the range C2:C13, type the below formula and press Ctrl + Shift + Enter to complete it:
To draw the trendline, select the sales and trend values (B1:C13) and make a line chart (Insert tab > Charts group > Line or Area Chart).
As the result, you have both the numeric values for the line of best fit returned by the formula and a visual representation of those values in a graph:
Projecting a future trend
To predict a trend for the future, you just need to include a set of new x-values in your TREND formula.
For this, we extend our time series with a few more month numbers and do trend projection by using this formula:
- B2:B13 is known_y's
- A2:A13 is known_x's
- A14:A17 is new_x's
Enter the above formula in cells C14:C17 and remember to press Ctrl + Shift + Enter to complete it appropriately. After that, create a new line chart for the extended data set (B1:C17).
The below screenshot shows the calculated new y-values and extended trendline:
Excel Trend formula for multiple sets of x-values
In situation when you have two or more sets of independent x values, enter them in separate columns, and supply that entire range to the known_x's argument of the TREND fucntion.
For example, with the known_x 1 values in B2:B13, known_x 2 values in C2:C13, and known_y values in D2:D13, you use the following formula to calculate trend:
Additionally, you can enter the new_x 1 and new_x 2 values in B14:B17 and C14:C17, respectively, and get the projected y-values with this formula:
If entered correctly (with the Ctrl + Shift + Enter shortcut), the formulas output the following results:
Other ways to do trend analysis in Excel
The TREND function is the most popular but not the only trend projection method in Excel. Below I will briefly describe a few other techniques.
Excel FORECAST vs TREND
"Trend" and "forecast" are very close concepts, but still there is a difference:
- Trend is something that represents the current or past days. For example, by analyzing the recent sales numbers, you can determine the cash flow trend and understand how your business has performed and is currently performing.
- Forecast is something that relates to the future. For example, by analyzing the historical data, you can project future changes and predict where current business practices will take you.
In terms of Excel, this distinction is not so obvious because the TREND function can not only calculate current trends, but also return future y-values, i.e. do trend forecasting.
The difference between TREND and FORECAST in Excel is as follows:
- The FORECAST function can only predict future values based on the existing values. The TREND function can calculate both current and future trends.
- The FORECAST function is used as a regular formula and returns a single new y-value for a single new-x value. The TREND function is used as an array formula and computes multiple y-values for multiple x-values.
When used for time series forecasting, both functions produce the same linear trend/forecast because their calculations are based on the same equation.
Please take a look at the screenshot below and compare the results returned by the following formulas:
Draw a trendline to visualize the trend
A trendline is commonly used to observe the general trend in your current data as well as project future data movements.
To add a trend to an existing chart, right-click the data series, and then click Add Trendline… This will create the default linear trendline for the current data and open the Format Trendline pane where you can choose another trendline type.
To forecast a trend, specify the number of periods under Forecast on the Format Trendline pane:
- To project the trend into the future, type the number of periods in the Forward box.
- To extrapolate a trend into the past, type the desired number in the Backward box.
To show the trendline equation, check the Display Equation on chart box. For better accuracy, you can show more digits in the trendline equation.
As shown in the image below, the results of the trendline equation are perfectly in line with the numbers returned by the FORECAST and TREND formulas:
For more information, please see How to add a trendline in Excel.
Smooth trend with moving average
Another simple technique that can help you show a trend is called moving average (aka rolling average or running average). This method smoothes out short-term fluctuations in a sample time series and highlights longer-term patterns or trends.
You can calculate moving average manually with your own formulas or have Excel make a trendline for you automatically.
To display a moving average trendline on a chart, here's what you need to do:
- Right-click the data series and click Add Trendline.
- On the Format Trendline pane, select Moving Average and specify the desired number of periods.
That's how you use the TREND function to calculate trends in Excel. To have a closer look at the formulas discussed in this tutorial, you are welcome to download our sample Excel TREND workbook. I thank you for reading and hope to see you on our blog next week!
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23 comments to "TREND function and other ways to do trend analysis in Excel"
I've been trending my stock investment value for several years with both linear and exponential trend lines. with all returns reinvested. As this is essentially a compound savings investment, it is more closely modeled by the exponential trend equation. I'd like to differentiate the equation to determine the current rate of return. Unfortunately, substituting a current date value for the exponential exponent (x) results in wildly inaccurate results. Then I realized that the displayed coefficient of x was rounded to 4 decimal places with a single digit in the 4th decimal place. By trial and error I was able to extend the accuracy to 7 decimal places (4 significant digits) and get accurate results for y given a value of x from the trend line. Is there any way to get more accuracy (at least 4 significant digits) in the displayed x coef. when it becomes extremely small? Manually doing this thru trial and error is quite time consuming!
@Jeff, have you tried right clicking on the trendline equation, then formatting as a number with as many decimals as you want?
expression A variable that represents a Trendlines object.
Parameters
| Name | Required/Optional | Data type | Description |
|---|---|---|---|
| Type | Optional | XlTrendlineType | The trendline type. |
| Order | Optional | Variant | Variant if Type is xlPolynomial. The trendline order. Must be an integer from 2 to 6, inclusive. |
| Period | Optional | Variant | Variant if Type is xlMovingAvg. The trendline period. Must be an integer greater than 1 and less than the number of data points in the series you are adding a trendline to. |
| Forward | Optional | Variant | The number of periods (or units on a scatter chart) that the trendline extends forward. |
| Backward | Optional | Variant | The number of periods (or units on a scatter chart) that the trendline extends backward. |
| Intercept | Optional | Variant | The trendline intercept. If this argument is omitted, the intercept is automatically set by the regression. |
| DisplayEquation | Optional | Variant | True to display the equation of the trendline on the chart (in the same data label as the R-squared value). The default value is False. |
| DisplayRSquared | Optional | Variant | True to display the R-squared value of the trendline on the chart (in the same data label as the equation). The default value is False. |
| Name | Optional | Variant | The name of the trendline as text. If this argument is omitted, Microsoft Excel generates a name. |
Return value
A Trendline object that represents the new trendline.
Example
This example creates a new linear trendline on Chart1.
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When plotting data in a graph, you may often want to visualize the general trend in your data. This can be done by adding a trendline to a chart. Luckily, Microsoft Excel has made inserting a trend line very easy, especially in newer versions. Nevertheless, there are a few little secrets that make a big difference, and I will share them with you in a moment.
Trendline in Excel
A trendline, also referred to as a line of best fit, is a straight or curved line in a chart that shows the general pattern or overall direction of the data.
This analytical tool is most often used to show data movements over a period of time or correlation between two variables.
Visually, a trendline looks somewhat similar to a line chart, but it doesn't connect the actual data points as a line chart does. A best-fit line shows the general trend in all the data, ignoring statistical errors and minor exceptions. In some cases, it can also be used to forecast trends.
Excel graphs that support trendlines
A trendline can be added to a variety of Excel charts, including XY scatter, bubble, stock, as well as unstacked 2-D bar, column, area and line graphs.
You cannot add a trendline to 3-D or stacked charts, pie, radar and similar visuals.
Below, there is an example of a scatter plot with an extended trendline:
How to add a trendline in Excel
In Excel 2019, Excel 2016 and Excel 2013, adding a trend line is a quick 3-step process:
- Click anywhere in the chart to select it.
- On the right side of the chart, click the Chart Elements button (the cross button), and then do one of the following:
- Check the Trendline box to insert the default linear trendline:
- Click the arrow next to the Trendline box and choose one of the suggested types:
- Click the arrow next to Trendline, and then click More Options. This will open the Format Trendline pane, where you switch to the Trendline Options tab to see all the trend line types available in Excel and choose the one you want. The default Linear trendline will be pre-selected automatically. Optionally, you can also display the trendline equation in the chart.
- Check the Trendline box to insert the default linear trendline:
How to make a trendline in Excel 2010
To add a trendline in Excel 2010, you follow a different route:
- On a chart, click the data series for which you want to draw a trendline.
- Under Chart Tools, go to the Layout tab > Analysis group, click Trendline and either:
- Pick one of the predefined options, or
- Click More Trendline Options…, and then choose the trendline type for your chart.
How to insert multiple trendlines in the same chart
Microsoft Excel allows adding more than one trendline to a chart. There are two scenarios that should be handled differently.
Add a trendline for each data series
To put a trendline on a chart that has two or more data series, here's what you do:
As the result, each data series will have its own trendline of the matching color:
Alternatively, you can click the Chart Elements button, then click the arrow next to Trendline and choose the type you want. Excel will show a list of the data series plotted in your chart. You pick the needed one and click OK.
Draw different trendline types for the same data series
To make two or more different trendlines for the same data series, add the first trendline as usual, and then do one of the following:
- Right-click the data series, select Add Trendline… in the context menu, and then choose a different trend line type on the pane.
- Click the Chart Elements button, click the arrow next to Trendline and choose the type you want to add.
Either way, Excel will display multiple trendlines in the chart, Linear and Moving average in our case, for which you can set different colors:
How to format a trendline in Excel
To make your graph even more understandable and easily interpreted, you may want to change the default appearance of a trendline. For this, right-click it and then click Format Trendline… . Or simply double-click the trendline to open the Format Trendline pane.
On the pane, switch to the Fill & Line tab and choose the color, width and dash type for your trendline. For example, you can make it a solid line rather than a dashed line:
How to extend trendline in Excel
To project the data trends into the future or past, this is what you need to do:
- Double-click the trendline to open the Format Trendline pane.
- On the Trendline Options tab (the last one), type the desired values in the Forward and/or Backward boxes under Forecast:
In this example, we choose to extend the trendline for 8 periods beyond the last data point:
Excel trendline equation
Trendline equation is a formula that mathematically describes the line that best fits the data points. The equations are different for different trendline types, though in every equation Excel uses the least squares method to find the best fit for a line though data points. You can find the equations for all Excel trendlines types in this tutorial.
When drawing the line of best fit in Excel, you can display its equation in a chart. Additionally, you can display the R-squared value.
R-squared value (Coefficient of Determination) indicates how well the trendline corresponds to the data. The closer the R 2 value to 1, the better the fit.
How to display the trendline equation on a chart
To show the equation and R-squared value on a chart, do the following:
- Double-click the trendline to open its pane.
- On the pane, switch to the Trendline Options tab and check these boxes:
- Display Equation on chart
- Display R-squared value on chart
This will put the trendline formula and the R 2 value at the top of your graph, and you are free to drag them wherever you see fit.
In this example, the R-squared value equals 0.957, which means that the trendline fits about 95% of data values.
Show more digits in the trendline equation
If the Excel trendline equation delivers inaccurate results when you supply x values to it manually, most likely it's because of rounding. By default, the numbers in the trendline equation are rounded to 2 - 4 decimal places. However, you can easily make more digits visible. Here's how:
- Select the trendline formula in the chart.
- On the Format Trendline Label pane that appears, go to the Label Options tab.
- In the Category drop-down list, select Number.
- In the Decimal places box, type the number of decimal places you want to show (up to 30) and press Enter to update the equation in the chart.
How to find the slope of a trendline in Excel
To get the slope of the linear trendline, Microsoft Excel provides a special function of the same name:
- Known_y's is a range of the dependent data points plotted on the y-axis.
- Known_x's is a range of the independent data points plotted on the x-axis.
With the x values in B2:B13 and the y values in C2:C13, the formula goes as follows:
The slope can also be calculated by using the LINEST function in a regular formula:
If entered as an array formula by pressing Ctrl + Shift + Enter , it would return the slope of the trendline and y-intercept into two adjacent cells in the same row. For more information, please see How to use the LINEST function in Excel.
As you can see in the following screenshot, the slope value returned by the formulas exactly matches the slope coefficient in the linear trendline equation displayed in our graph:
The coefficients of other trendline equation types (Exponential, Polynomial, Logarithmic, etc.) can also be calculated, but you'd need to use more complex formulas explained in Excel trendline equations.
How to delete a trendline in Excel
To remove a trendline from your chart, right-click the line, and then click Delete:
Or click the Chart Elements button and unselect the Trendline box:
Either way, Excel will immediately remove the trendline from a chart.
That's how to do a trendline in Excel. I thank you for reading and hope to see you on our blog next week!
In this tutorial, you will find the detailed description of all the trendline options available in Excel and when to use them. You will also learn how to display a trendline equation in a chart and find the slope of trendline.
It is very easy to add a trendline in Excel. The only real challenge is to choose the trendline type that best corresponds to the type of data you are analyzing. In this tutorial, you will find the detailed description of all the trendline options available in Excel and when to use them. If you are looking for how to insert a trendline in an Excel chart, please check out the above linked tutorial.
Excel trendline types
When adding a trendline in Excel, you have 6 different options to choose from. Additionally, Microsoft Excel allows displaying a trendline equation and R-squared value in a chart:
- Trendline equation is a formula that finds a line that best fits the data points.
- R-squared value measures the trendline reliability - the nearer R 2 is to 1, the better the trendline fits the data.
Below, you will find a brief description of each trendline type with chart examples.
Linear trendline
The linear trend line is best to be used with linear data sets when the data points in a chart resemble a straight line. Typically, a linear trendline describes a continuous rise or fall over time.
For example, the following linear trendline shows a steady increase in sales over 6 months. And the R 2 value of 0.9855 indicates a pretty good fit of the estimated trendline values to the actual data.
Exponential trendline
The exponential trendline is a curved line that illustrates a rise or fall in data values at an increasing rate, therefore the line is usually more curved at one side. This trendline type is often used in sciences, for example to visualize a human population growth or decline in wildlife populations.
Please note that an exponential trendline cannot be created for data that contains zeros or negative values.
A good example of an exponential curve is the decay in the entire wild tiger population on the earth.
Logarithmic trendline
The logarithmic best-fit line is generally used to plot data that quickly increases or decreases and then levels off. It can include both positive and negative values.
An example of a logarithmic trendline may be an inflation rate, which first is getting higher but after a while stabilizes.
Polynomial trendline
The polynomial curvilinear trendline works well for large data sets with oscillating values that have more than one rise and fall.
Generally, a polynomial is classified by the degree of the largest exponent. The degree of the polynomial trendline can also be determined by the number of bends on a graph. Typically, a quadratic polynomial trendline has one bend (hill or valley), a cubic polynomial has 1 or 2 bends, and a quartic polynomial has up to 3 bends.
When adding a polynomial trendline in an Excel chart, you specify the degree by typing the corresponding number in the Order box on the Format Trendline pane, which is 2 by default:
For example, the quadratic polynomial trend is evident on the following graph that shows the relationship between the profit and the number of years the product has been on the market: rise in the beginning, peak in the middle and fall near the end.
Power trendline
The power trend line is very similar to the exponential curve, only it has a more symmetrical arc. It is commonly used to plot measurements that increase at a certain rate.
A power trendline cannot be added to an Excel chart that contains zero or negative values.
As an example, let's draw a power trendline to visualize the chemical reaction rate. Note the R-squared value of 0.9918, which means that our trendline fits the data almost perfectly.
Moving average trendline
When the data points in your chart have a lot of ups and downs, a moving average trendline can smooth the extreme fluctuations in data values to show a pattern more clearly. For this, Excel calculates the moving average of the number of periods that you specify (2 by default) and puts those average values as points in the line. The higher the Period value, the smoother the line.
A good practical example is using the moving average trendline to reveal fluctuations in a stock price that otherwise would be difficult to observe.
Excel trendline equations and formulas
This section describes the equations that Excel uses for different trendline types. You do not have to build these formulas manually, simply tell Excel to display the trendline equation in a chart.
Also, we will discuss the formula to find the slope of a trendline and other coefficients. The formulas assume that you have 2 sets of variables: independent variable x and dependent variable y. In your worksheets, you can use these formulas to get the predicted y values for any given values of x.
For consistency, we will be using the same data set with slightly varying values for all the examples. However, please keep in mind that it's only for demonstration purposes. In your real worksheets, you should choose the trendline type corresponding to your data type.
Important note! The trendline formulas should only be used with XY scatter charts because only this chart plots both x and y axes as numeric values. For more information, please see Why Excel trendline equation may be wrong.Linear trendline equation and formulas
The linear trendline equation uses the least squares methods to seek the slope and intercept coefficients such that:
- b is the slope of a trendline.
- a is the y-intercept, which is the expected mean value of y when all x variables are equal to 0. On a chart, it's the point where the trendline crosses the y axis.
For linear regression, Microsoft Excel provides special functions to get the slope and intercept coefficients.
Slope of trendline
b: =SLOPE(y,x)
Y-intercept
a: =INTERCEPT(y,x)
Assuming the x range is B2:B13 and the y range is C2:C13, the real-life formulas go as follows:
The same results can be achieved by using the LINEST function as an array formula. For this, select 2 adjacent cells in the same row, enter the formula and press Ctrl + Shift + Enter to complete it:
As shown in the screenshot below, the slope and intercept coefficients returned by the formulas are perfectly in line with the coefficients in the linear trendline equation displayed in the chart, only the latter are rounded to 4 decimal places:
Exponential trendline equation and formulas
For the exponential trendline, Excel uses the following equation:
Where a and b are calculated coefficients and e is the mathematical constant e (the base of the natural logarithm).
The coefficients can be calculated by using these generic formulas:
a: =EXP(INDEX(LINEST(LN(y), x), 1, 2))
b: =INDEX(LINEST(LN(y), x), 1)
For our sample data set, the formulas take the following shape:
a: =EXP(INDEX(LINEST(LN(C2:C13), B2:B13), 1, 2))
b: =INDEX(LINEST(LN(C2:C13), B2:B13), 1)
Logarithmic trendline equation and formulas
Here's the logarithmic trendline equation in Excel:
Where a and b are constants and ln is the natural logarithm function.
To get the constants, use these generic formulas, which only differ in the last argument:
a: =INDEX(LINEST(y, LN(x)), 1)
b: =INDEX(LINEST(y, LN(x)), 1, 2)
For our sample data set, we use these ones:
a: =INDEX(LINEST(C2:C13, LN(B2:B13)), 1)
b: =INDEX(LINEST(C2:C13, LN(B2:B13)), 1, 2)
Polynomial trendline equation and formulas
To work out the polynomial trendline, Excel uses this equation:
Depending on the degree of your polynomial trendline, use one of the following sets of formulas to get the constants.
Quadratic (2nd order) polynomial trendline
Equation: y = b2x 2 + b1x + a
a: =INDEX(LINEST(y, x^), 1, 3)
Cubic (3rd order) polynomial trendline
a: =INDEX(LINEST(y, x^), 1, 4)
The formulas for higher degree polynomial trendlines can be built by using the same pattern.
For our data set, the 2 nd order polynomial trendline suites better, so we are using these formulas:
a: =INDEX(LINEST(C2:C13, B2:B13^), 1, 3)
Power trendline equation and formulas
A power trendline in Excel is drawn based on this simple equation:
Where a and b are constants, which can be calculated with these formulas:
a: =EXP(INDEX(LINEST(LN(y), LN(x),,), 1, 2))
b: =INDEX(LINEST(LN(y), LN(x),,), 1)
In our case, the following formulas work a treat:
a: =EXP(INDEX(LINEST(LN(C2:C13), LN(B2:B13),,), 1, 2))
b: =INDEX(LINEST(LN(C2:C13), LN(B2:B13),,), 1)
Excel trendline equation is wrong - reasons and fixes
If you think that Excel has drawn a trendline incorrectly or the trendline formula displayed in your chart is wrong, the following two points may shed some light on the situation.
Excel trendline equation is correct only in scatter charts
Excel trendline formulas should only be used with XY (scatter) graphs because only in this chart type both the y-axis and x-axis are plotted as numeric values.
In line charts, column and bar graphs, numeric values are plotted only on the y-axis. The x-axis is represented by a linear series (1, 2, 3,…) regardless of whether the axis labels are numbers or text. When you make a trendline in these charts, Excel uses those assumed x-values in the trendline formula.
Numbers are rounded in Excel trendline equation
To occupy less space in the chart, Excel displays very few significant digits in a trendline equation. Nice in terms of design, it significantly reduces the formula's accuracy when you manually supply x values in the equation.
An easy fix is to show more decimal places in the equation. Alternatively, you can calculate the coefficients by using a formula corresponding to your trendline type, and format the formula cells so that they show a sufficient number of decimal places. For this, simply click the Increase Decimal button on the Home tab in the Number group.
That's how you can make different trendline types in Excel and get their equations. I thank you for reading and hope to see you on our blog next week!
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54 comments to "Excel trendline types, equations and formulas"
My trendline plots correctly but the trendline equation solution for y yields incorrect y values. The equation is a 6th-degree polynomial. The correct y values range from -20 to 80. The x values range from 1900 to 2050. The incorrect y values are all in the range of -2.38E+15, plus and minus. I increased the decimal value to 30, but that did not affect the outcome. Any suggestion on how to fix this problem?
Masterful job. College professors take note. Teach in understandable ways so that students can take practical knowledge with them. You don.t need to prove how smart you are.
From a series of absolute numbers, which happen to be future quarterly estimates, I would like to calculate a growth rate. Is that possible and if so what would be the Excel formula code? merci
And if any of the numbers had negative values would that negate the exercise or is there a work around?
Hello!
Here is the article that may be helpful to you: Calculating percent change
Also pay attention to the article: How to calculate percent variance for negative numbers
I hope I answered your question. If you have any other questions, please don’t hesitate to ask.
This is very helpful information. I am confused though on how to calculate a value from the Power Law trendline in Excel. For instance, the trendline that I am looking at has values from 100 - 700 on the x-axis, 10,000 - 50,000 on the y-axis, and a curve that is asymptotic to both axes, decreasing from right to left. The provided trendline equation is y = 3E + 08x^(-1.611). What in the world does this mean?! Plugging any value of x into the equation produces a value of y = 3E + 0!
Your help is much appreciated!
Hi, thanks for this very useful guide. I have calculated the a,b,c coefficients for my binomial equation (y = ax2+bx+c). From here, how do I compare this model with my actual data and calculate the R2 ?
problem solved - used log (x) as new column and then do straight polynomial fitting on that!
Help. I am trying to extract all the coefficients of this formula: y=10^(ax^4+bx^3+cx^2+dx+e)
but not working (esp the array part of the input), could someone shed some light please?
Thank-you this was exactly what I needed
glad to see people finding it useful, wish I could apply it too. I have a column of sales we've made thus far and have it plotted on a chart, where I also use plynomial trendline. how can I using the formulas above get the value of trendline at the end of period?
thanks, appriciate support
WHAT IS THE DIFFERENCE BETWEEN POLYNOMIAL ORDER 3 AND 4
great, thanks I tried with poly of order 3 (ax3 + bx2 + cx1 + x0)
it works perfectly and avoids me to make a trendline and manually copy the results
a possible improvement would be to allow the use of =na() for some empty cells (because I have differenet lines and x not always the same -results of measurements-) this is possible with graph
How should I address those issues?
Thank you again for the help!
I am looking for advice (please have a look on formulas):
=LINEST(,)
work fine and calculate a,b for y=ax+b
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