deletions | additions       diff --git a/introduction.md b/introduction.md  index d756945..89a6188 100644  --- a/introduction.md  +++ b/introduction.md 
...
To add a new covariate, go to the [new  covariate](http:www.betydb.org/covariates/new) page  ### Extracting information from tables and graphs   1. Identify the data that is associated with each treatment  *note:* If the experiment has many factors, the paper may not report the mean and statistics for each treatment. Often, the reported data will reflect the results of more than one treatment (for example, if there was no effect of the treatment on the quantity of interest). In some cases it will be possible to obtain the values for each treatment, e.g. if there are _n-1_ values and _n_ treatments. If this is not the case, the treatment names and definitions should be changed to indicate the data reflect the results of more than one experimental treatment.   2. Enter the mean value of the trait  3. Enter the `statname`, `stat`, and number of replicates, `n`  associated with the mean  * `stat` is the value of the `statname` (i.e. `statname` might be  ’standard deviation’ (SD) and the `stat` is the numerical value  of the statistic)  * Always measure size of error bar from the mean to the end of an  error bar. This is the value when presented as ( _X_ ± _SE_) or  _X(SE)_ and may be found in a table or on a graph.  * Sometimes CI and LSD are presented as the entire range from the  lower to the upper end of the confidence interval. In this case,  take 1/2 of the interval representing the distance from the mean  to the upper or lower bound  #### Extracting Data using R  To extract data from a jpg file in R using the digitize package:   1. Save image as a `*.jpg` file  2. Open R  3. Change the directory that R is using to the one where the image is  4. Use R code below to extract data, display it, and save it in a `csv`  file (steps below)  5. Upload csv to the project file in google spreadsheet, or open as  excel/openoffice and copy/paste to google spreadsheet    #### Extracting Data From a Figure using GetData  1. Open PDF in Adobe Reader.  2. Zoom in on the figure  3. Choose `Tools` → `Select and Zoom`  4. Open Paint  5. Paste Picture  6. Save as `authorYYYYabc\_figX.jpg`  7. Open Get Data  8. `File` → `open` open figure  9. Select button with two arrows (fourth from left)  10. Follow instructions to select x min, x max, y min and y max. If the  x-axis has a categorical variable, it does not matter what values  you use for x min and x max.  11. Make sure to set the correct values for the max and min of each  axis, and indicate if the axis is log-scaled  12. Select the target button (seven from left)  13. Click over center of desired data points and error bars  14. Copy data to a Google spreadsheet. See [Google Spreadsheets] (#Section 3).  15. Calculate SE as the distance between the error bar upper bound and  the mean (absolute value of difference between the two points)  ### Adding a PFT, Species, and Cultivar  Plant functional types (PFTs) are used to group plants for statistical