A heat graph is commonly used come display readjust over time as a collection of data points linked by straight line segment on 2 axes. The heat graph as such helps to identify the relationship in between two sets of values, with one data collection always gift dependent top top the various other set.

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Line graphs are drawn so the the independent data room on the horizontal a-axis (e.g. Time) and the dependency data room on the vertical y-axis.Line graphs are offered to track changes over short and long periods of time.There is some debate around the level of measurement in between time points. Some say the data should be measured nearly continually in order because that the lines to be exact representations. Others feel a monthly measure up is sufficient, even though the line implies data in ~ points where no measurement to be taken.

Line graphs are advantageous in that they present data variables and also trends very plainly and can assist to make predictions about the outcomes of data no yet recorded. Lock can likewise be supplied to display several dependence variables against one live independence variable. When comparing data sets, heat graphs room only helpful if the axes follow the very same scales. Some experts recommend no an ext than 4 lines on a solitary graph; any more than that and it becomes complicated to interpret.

"Line graphs and scatterplotsare comparable in the they document individual data values as marks on a graph. The difference in between these two layouts is exactly how the heat is created. In line graphs, the heat is developed by connecting every individual data allude to present local changes, in this way, the local readjust from allude to point can it is in seen. This is done when it is important to have the ability to see the local adjust between pair of points. An in its entirety trend can still it is in seen, yet this tendency is joined by the neighborhood trend in between individual or little groups of points, conversely, the heat of the scatterplot go not attach individual points but instead reflects the trend adhered to by the data."

Line graphs that affix only two points over time are dubbed slope graphs. These have the right to be handy when you don’t have actually data because that each time period, yet want come compare, for example, the start of the regimen in 1986 come the existing state the the program in 2014. Use these if friend don’t have other data to display program outcomes.

### Example

The differencein median family income in between California and also the remainder of the united States

This instance from the California spending plan Project is anexample that a line chart showing readjust in median family income in California between 1989 and 2010. The colour distinction outlines the difference between California and also the unified States

Source: www.cbp.org/pdfs/2012/TestImages/Second%20Test/line-chart-template.png

Red river discharge rate per month in 1993

"This example might have likewise been developed as a bar graph. You would usage a heat graph as soon as you desire to be able to more clearly see the rate of adjust (slope) in between individual data points. If the live independence variable to be nominal, girlfriend would virtually certainly usage a bar graph instead of a line graph."

"Here, we have taken the same graph seen over and added a 2nd independent variable, year. Both the independent variables, month and year, deserve to be treated together being either as ordinal or scalar. This is often the case with larger units of time, such as weeks, months, and also years. Since we have actually a second independent variable, some kind of coding is required to show which level (year) each line is. Though we might label each bar with text indicating the year, that is more efficient to usecolorand/or a various symbol ~ above the data points. Us will need a legend to define the coding scheme.

Multiple line graphs have actually space-saving qualities over a comparable grouped bar graph. Because the data worths are significant by tiny marks (points) and also not bars, they carry out not have to be offset from each various other (only as soon as data values are really dense does this come to be a problem). Another benefit is the the lines have the right to easily double coded. With the lines, they deserve to both becolorcoded (for computer system andcolorprint display) or shape coded with symbols (for black & white reproduction). With bars, shape coding cannot be used, and pattern coding needs to be substituted. Sample coding often tends to it is in much more limiting.

Notice that there is a break in the 1996 data line (green/triangle) in between August and also October. Due to the fact that the data point for September is missing, the line must not be associated between August and October since this would give an erroneous regional slope. This is particularly important if you display screen the line without symbols at individual data points."

Source: Wallace, (2005)www.ncsu.edu/labwrite/res/gh/gh-linegraph.html#multipleline

Advice for picking this option (tips and traps)

Line graphs space usually provided to represent alters over time.

Advice for using this option (tips and also traps)

As best as possible, brand the line with its name rather than utilizing a legend.

Highlight important points in the line through the exact value, such together the highest and also lowest point out or those points where actual data arsenal occured.

### Resource

Example

Line Graphs and also Scatter Plots: This website from phibìc Carolina State University has actually guided instances forusing heat graphs.

### Other ways to visualise changesover time

SlopegraphComparing readjust between 2 points over time with a line.

Split Axis Bar graphRegraphingcomparison in between two points with time by merely graphing the readjust that has developed in that time frame.

Stacked GraphVisualising just how a team of quantities transforms over time. Items space "stacked" in this kind of graph enabling the user to add up the basic data points.

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