P366: Lecture #1 Use of Excel for analysis Lei Chen, MD Jan 6, 2002

Administration Course web site all course material will be posted there Group assignment - self selected groups - max of 5 people per group - submit group information in today’s lab

Class Objectives Provide students with the basic data management and statistical analysis skills An opportunity to apply basic statistical knowledge Practice, practice and practice

Structure of Course Four major lectures, supplemented by lab sessions –Lec #1: Microsoft Excel –Lec #2: Basic Microsoft Access –Lec #3: Advanced Microsoft Access –Lec #4: SPSS

Introduction to Microsoft Excel An electronic spreadsheet program Very popular and widely used Multiple functions provided, such as graphing, statistical tools, financial analysis tools, data mapping tools, etc. We will use version Excel 97

Excel Basics Understanding Excel 97 Screen –Excel icon –Title bar –Menu bar –Tool bars –Formula bar –Scroll bar

Excel Basics Terminology – File a file is operated through a window a file can have multiple worksheets –Worksheet a rectangular grid maximum size for a worksheet is 66,536 rows by 256 columns Can also store graphs

Excel Basics Terminology –Cell addressable unit of a worksheet can store different data types numerical text date / time formula,etc

Excel Basics Manipulating windows Maximize, minimize, close Manipulating files Create, open, save Manipulating worksheets Insert, delete, copy/move, rename

Excel Basics Where can I find the commands –Menu –Tool bar –Right mouse button

Entering data Cell by cell Click a cell, type, move to next cell to enter more data Auto-complete Use of file handles to copy, or create a series Importing external file

Selecting data Selecting cells Selecting columns / rows Selecting a data block Selecting the whole worksheet

Editing Data Move a region Cut - paste, or drag - drop Copy a region Copy – paste Paste special Insert cell / column / row Delete cell / column / row Undo / redo

Formatting Data First select a region you want to format Formatting cells –Formatting numerical data –Font type, style, size and color –background color –Alignment: left, center, right, text rotation –Others to improve the display

Formatting Data Formatting columns / rows –Determine row height and column width –Hide / uncover to simplify the view of a complex worksheet Formatting entire worksheet –Hide / uncover –Selecting a background

Basic Data Processing Sort –You must select all columns/rows that you want to remain related Filter –A quick and easy way to find and work with a subset of data which meet the criteria you specify –The order of data will not change Name box Add comments

Advanced Data Processing Graphics Excel formulas Excel analysis ToolPak

Graphics Follow the instructions Select the graph type you need Specify the data for X-axis and Y-axis Name X and Y axis, title the graph

Excel Formula Excel supports a variety of functions A formula can consist of function name, operators, cell references Copy a formula: use of fill handle All formulas start with “=”

Excel Formula Use of cell reference in a formula –Cell reference can be entered in two ways: typed, or selected using mouse – Relative reference change when you move or copy a formula – Absolute reference stay the same type in $ sign, i.e. $E$5

Excel Formula Examples –Arithmetic operations: sum, aver, max, min –Logical function, “if” IF(A3=“PAXIL”, 1, 0) IF(A3=“PAXIL”, 2, IF(A3=“Prozac”, 1, 0)) –Calculate age using two dates

Excel AnalysisToolPak Go to “Tool” in menu, then Data analysis A variety of statistical analysis available Two examples – T-test – Regression

Example-Ttest Comparing two group means Sorting data first according to the intervention variable

Example - regression Prepare independent and dependent variables, including dummy variables Use Excel formula Specify the data as independent and dependent variables It is easy, isn’t it?

Summary Those are the Excel Basics Excel has limitations –If you wish to manage large or sophisticated database, you may use Access –If you analysis is large or sophisticated, you may want to use others, i.e. SPSS