Adding error bars to line plots of means in EXCEL

1. Enter the values of the variable to be plotted in one row and the standard errors pertaining to each variable column in another row.
2. Highlight the row containing the variable values
3. Click on the chart wizard icon (identified by a graph of coloured bars) or choose CHART on the INSERT toolbar

4. Under CHART TYPE choose LINE and choose LINE WITH MARKERS DISPLAYED AT EACH DATA POINT under CHART SUB-TYPE. Click NEXT

5. Let us assume we have the following input for age (young, old) and clinical group (control, patient) with means and width of confidence interval half width equal to upper limit - mean. Confidence intervals can be obtained e.g. using ANALYZE:DESCRIPTIVE STATISTICS:EXPLORE in SPSS.

1. Doubleclick on any bar in the resultant graph

2. Click on the tab called Y ERROR BARS in the resultant FORMAT DATA SERIES Window

3. Click on the display named BOTH and choose CUSTOM

4. Highlight the standard error row in the spreadsheet. The co-ordinates of the standard error row should appear in the '+' box in the CUSTOM section

5. Click on the window adjacent to '-' and highlight the standard error row. The co-ordinates of the standard error row should appear in the '-' box

6. Click OK You should now have a bar chart with error bars. Doubleclicking on the error bars and clicking the PATTERNS tab in the FORMAT ERROR BARS window allows the user to change the style, colour or thickness of the lines forming the error bars.