How to remove duplicate rows but keep one

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What is a duplicate row in Excel?

A duplicate row in Excel is an entire row where all values across specified columns match exactly with another row, creating redundant data entries. This differs from single-cell duplicates, as Excel evaluates the full row or selected columns for identical content, such as matching patient IDs, dates, and treatments in clinical trial datasets.

Why does removing duplicates matter for data analysis?

Removing duplicates ensures data integrity by eliminating redundancies that inflate counts and distort summaries. Accurate totals, averages, and trends emerge without artificial repetition, critical for statistical validity in biostatistics or SDTM/ADaM workflows.

Duplicates skew pivot tables, charts, and formulas like SUM or COUNTIF, leading to erroneous insights. Survival analysis or QC validation fails when repeated rows double-count events, violating regulatory standards.

Clean datasets speed up processing in SAS/R exports from Excel and reduce file sizes for efficient handling. Proactive deduplication supports reproducible analysis pipelines in clinical research.

How to remove duplicate rows but keep one using the remove duplicates tool

To remove duplicate rows but keep one using the Remove Duplicates tool, follow these steps:

1. Select your data range containing the duplicate rows
2. Go to the Data tab on the ribbon
3. Click Remove Duplicates in the Data Tools group
4. Choose the columns you want to evaluate for duplicates in the dialog box
5. Click OK to confirm

Excel scans the selected columns and deletes later duplicates, keeping the topmost occurrence. This method modifies the original dataset directly and handles large ranges quickly.

How to remove duplicate rows but keep one using the UNIQUE function

To remove duplicate rows but keep one using the UNIQUE function, follow these steps:

1. Click on an empty cell where you want the unique results to appear
2. Enter the formula =UNIQUE(range) specifying your data range
3. Press Enter to execute the formula

The function spills unique rows dynamically, preserving the first instance without altering source data. You can use =UNIQUE(A1:C100, FALSE, FALSE) with FALSE arguments to specify row-based extraction. Copy and paste the results as values over the originals when you need a static list.

How to remove duplicate rows but keep one using Power Query Editor

To remove duplicate rows but keep one using Power Query Editor, follow these steps:

1. Select your data range
2. Go to Data tab and click From Table/Range to load the data
3. Go to Home tab and click Remove Duplicates
4. Preview the results to verify the first row per unique combination is retained
5. Click Close & Load to export the cleaned data to a new sheet

Remove Duplicates in Power Query evaluates all columns in the table, not just selected columns. This method suits repeatable workflows in SDTM/ADaM data cleaning, as it refreshes automatically with source changes.

How to remove duplicate rows but keep one using a helper formula

To remove duplicate rows but keep one using a helper formula, follow these steps:

1. Add a new column next to your data
2. Enter the formula =IF(COUNTIF($A$2:A2,A2)=1,A2,"") in the first cell of the helper column
3. Copy the formula down to all rows in your dataset
4. Filter or sort the data to hide blank cells
5. Delete the rows with blank values in the helper column

This method flags the first instance of each value. The formula checks whether the current cell value appears for the first time by counting occurrences from the start of the range to the current row. A count of 1 indicates the first instance. You can adjust the formula for multi-column keys. This approach gives visibility before permanent changes, useful for QC validation.

How to remove duplicate rows but keep one using a VBA macro

To remove duplicate rows but keep one using a VBA macro, follow these steps:

1. Press Alt+F11 to open the Visual Basic Editor
2. Click Insert in the menu bar and select Module
3. Enter the following code in the module window:

Sub RemoveDuplicateRows()
    Dim ws As Worksheet
    Set ws = ActiveSheet
    ws.Range("A1:E100").RemoveDuplicates Columns:=Array(1, 2, 3, 4, 5), Header:=xlYes
End Sub

4. Press F5 or click Run to execute the macro

Customize the range reference (A1:E100) and column array to match your dataset. This method automates batch processing for statistical programming tasks and handles repetitive deduplication workflows efficiently.

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