Basics of SPSS, Part 1
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Basics of SPSS, Part 1

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Getting started with SPSS, defining variables, entering data and importing data from Excel

Getting started with SPSS, defining variables, entering data and importing data from Excel

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  • Indicate your level of agreement with the following question:“Most days,my commute causes me to feel stressed when I arrive at university”.(1 = Strongly disagree, 2 = Disagree, 3 = I don’t know, 4 = Agree, 5 = Strongly Agree)
  • Indicate your level of agreement with the following question:“Most days,my commute causes me to feel stressed when I arrive at university”.(1 = Strongly disagree, 2 = Disagree, 3 = I don’t know, 4 = Agree, 5 = Strongly Agree)
  • Indicate your level of agreement with the following question:“Most days,my commute causes me to feel stressed when I arrive at university”.(1 = Strongly disagree, 2 = Disagree, 3 = I don’t know, 4 = Agree, 5 = Strongly Agree)
  • Indicate your level of agreement with the following question:“Most days,my commute causes me to feel stressed when I arrive at university”.(1 = Strongly disagree, 2 = Disagree, 3 = I don’t know, 4 = Agree, 5 = Strongly Agree)

Basics of SPSS, Part 1 Basics of SPSS, Part 1 Presentation Transcript

  • Part 1: Getting started entering data and defining variables Dr.ChristinePereira 1
  • Dr.ChristinePereira » Purpose and use of SPSS » Open SPSS » What is a Variable? » Defining variables in SPSS » Entering Data » Open and save data files » Import data from Excel » Handling missing data ASK at Brunel (2014) 2
  • Dr.ChristinePereira » SPSS is a Statistical Software Package » SPSS is a tool It only does what it’s ‘told’ to do. It does not think for you It is not a black box » You need to know the correct statistics for your research BEFORE using SPSS. » If you understand the statistics, then you are ready to do analysis in SPSS. ASK at Brunel (2014) 3
  • Click on the Windows Start Icon Type SPSS 20 into the search box Select SPSS 20 from the list 1 2 3 Dr.ChristinePereira ASK at Brunel (2014) 4
  • Open NEW data file Dr.ChristinePereira ASK at Brunel (2014) 5
  • Dr.ChristinePereira ASK at Brunel (2014) 6 Enter variable names in the first column of Variable View.
  • Dr.ChristinePereira ASK at Brunel (2014) 7 Enter the data for each variable. Each variable name will appear as a column heading replacing var.
  • What is a variable? How do we define variables in SPSS? Dr.ChristinePereira ASK at Brunel (2014) 10
  • Dr.ChristinePereira » A measurement: A characteristic + E.g., Gender, Age, Height, Weight… Time points + E.g., pre-test, post-test, T0, T1, T2… Experimental Condition + E.g., Condition, Experimental group… Opinion/belief + E.g., A survey question which asks for a respondent’s level of agreement with a statement Etc… ASK at Brunel (2014) 11
  • Dr.ChristinePereira ASK at Brunel (2014) 12 What is your gender? Male or Female
  • Dr.ChristinePereira ASK at Brunel (2014) 13 How long does it take, on average, to commute into Uni?
  • Dr.ChristinePereira ASK at Brunel (2014) 14 What is your main mode of transport to Uni?
  • Dr.ChristinePereira ASK at Brunel (2014) 15 Indicate your level of agreement with this statement: “Most days, my commute causes me to feel stressed when I arrive at university”.
  • Dr.ChristinePereira » Random sample of 200 residents of Uxbridge. » Asked respondents’ their view on stem cell research using a 3 pt. Likert Scale (Disagree, No Opinion, Agree). » Asked respondents’ if they believed global warming was an important issue using a 5 pt. Likert Scale (Strongly Disagree to Strongly Agree). ASK at Brunel (2014) 16 Questionnaire Responses
  • Dr.ChristinePereira » Random sample of 200 residents of Uxbridge. » Asked respondents’ their view on stem cell research using a 3 pt. Likert Scale (Disagree, No Opinion, Agree). » Asked respondents’ if they believed global warming was an important issue using a 5 pt. Likert Scale (Strongly Disagree to Strongly Agree). ASK at Brunel (2014) 17 Questionnaire Responses
  • Dr.ChristinePereira ASK at Brunel (2014) 18 Resident StemCell GlobalWarming 1 Agree Strongly Agree 2 Undecided Agree 3 Undecided Strongly Disagree 4 Disagree Undecided … … … Questionnaire Responses
  • Dr.ChristinePereira ASK at Brunel (2014) 19 Experimental Condition Cond 1 and 2 are independent, NOT repeated measures.
  • Dr.ChristinePereira ASK at Brunel (2014) 20 Score on a test
  • Dr.ChristinePereira » 30 participants were used to investigate the effect of caffeine on their ability to sleep. » The 30 participants were randomly assigned to one of 2 conditions: No caffeine (control) or one dose of caffeine every 3 hours from 9am-6pm. » The study measured participants ability to sleep by taking the average number of hours slept per night over a 2 week period. ASK at Brunel (2014) 21 Caffeine and Sleep
  • Dr.ChristinePereira » 30 participants were used to investigate the effect of caffeine on their ability to sleep. » The 30 participants were randomly assigned to one of 2 conditions: No caffeine (control) or one dose of caffeine every 3 hours from 9am-6pm. » The study measured participants ability to sleep by taking the average number of hours slept per night over a 2 week period. ASK at Brunel (2014) 22 Caffeine and Sleep
  • Dr.ChristinePereira ASK at Brunel (2014) 23 Participant Condition AvgHoursSlept 1 Control 7.2 2 Caffeine 6.7 3 Caffeine 6.3 4 Control 6.9 … … … Caffeine and Sleep
  • Dr.ChristinePereira ASK at Brunel (2014) 24 Status when admitted to care facility
  • Dr.ChristinePereira ASK at Brunel (2014) 25 Anxiety level measured at 3 time points for each participant
  • Dr.ChristinePereira ASK at Brunel (2014) 26 Why not enter TIME as 1 variable like we did for STATUS?
  • Dr.ChristinePereira » 50 participants of varying fitness levels were used to investigate whether personal trainers make a significant difference in ones fitness. » Participants were randomly assigned to one of two training groups: self training or professional trainer. » Each participants 1 mile time (in mins) was recorded 2 days prior to the start of the study. » Each group then followed a specific training regime for 30 days and their 1 mile time (in mins) recorded again. ASK at Brunel (2014) 27 Fitness Regime
  • » 50 participants of varying fitness levels were used to investigate whether personal trainers make a significant difference in ones fitness. » Participants were randomly assigned to one of two training groups: self training or professional trainer. » Each participants 1 mile time (in mins) was recorded 2 days prior to the start of the study. » Each group then followed a specific training regime for 30 days and their 1 mile time (in mins) recorded again. Dr.ChristinePereira ASK at Brunel (2014) 28 Fitness Regime Pre-test and Post-test
  • Dr.ChristinePereira ASK at Brunel (2014) 30 Fitness Regime Participant Training Pre_Mile Post_Mile 1 Self 15.3 14.1 2 Professional 16.1 14.9 3 Self 20.5 16.8 4 Self 16.8 16.2 … … … …
  • Dr.ChristinePereira ASK at Brunel (2014) 31 Variables Categorical Qualitative Scale Quantitative Nominal (Unranked categories)  Marital Status  Political Party  Eye Color Ordinal (Ranked categories)  Satisfaction level  Level of agreement Not grouped  Height  Weight  Age  No. of cars  No. of students • In SPSS, data is either Nominal, Ordinal or Scale. • It is essential to classify data correctly. - Incorrect classification… may result in incorrect analyses.
  • Code categorical variables Enter data Dr.ChristinePereira ASK at Brunel (2014) 32
  • Dr.ChristinePereira ASK at Brunel (2014) 33 Level of Measurement? Categorical variables need to be coded Scale variables do not need to be coded
  • Dr.ChristinePereira ASK at Brunel (2014) 34 Level of Measurement? 0 = Male 1 = Female 1 0 1 1 1 1 0 0 0 0
  • Dr.ChristinePereira ASK at Brunel (2014) 35 Level of Measurement? Scale, does not need to be coded
  • Dr.ChristinePereira ASK at Brunel (2014) 36 1 = tfl (i.e. public transport) 2 = Car 3 = Cycle 4 = Walk 1 2 3 4 2 1 1 1 1 1 Level of Measurement?
  • Dr.ChristinePereira ASK at Brunel (2014) 37 Indicate your level of agreement with the following statement: “Most days, my commute causes me to feel stressed when I arrive at university”.
  • Dr.ChristinePereira ASK at Brunel (2014) 38 1 = Strongly Disagree 2 = Disagree 3 = I don’t know 4 = Agree 5 = Strongly Agree Level of Measurement?
  • Dr.ChristinePereira ASK at Brunel (2014) 39 Data has been coded Now we’re ready to enter it in SPSS
  • Dr.ChristinePereira ASK at Brunel (2014) 40 1. Enter & define variables from Variable View. • Variable names • Must begin with a letter • No spaces and no special characters (except _ )
  • Dr.ChristinePereira ASK at Brunel (2014) 41 1. Enter & define variables from Variable View. • Type • Should (almost) always be numeric • SPSS cannot analyse non-numeric data
  • Dr.ChristinePereira ASK at Brunel (2014) 42 1. Enter & define variables from Variable View. • Decimals • How many decimal places do you want to see in the Data View?
  • Dr.ChristinePereira ASK at Brunel (2014) 43 1. Enter & define variables from Variable View. • Label • IMPORTANT!!! Make good labels! • Short description of the variable • This is what will be written on all graphs & tables
  • Dr.ChristinePereira ASK at Brunel (2014) 44 1. Enter & define variables from Variable View. • Values (i.e., Value labels) • IMPORTANT!!! - Tell SPSS what all the codes represent! • This is what is written on all graphs & tables
  • Dr.ChristinePereira ASK at Brunel (2014) 45 1. Enter & define variables from Variable View.
  • Dr.ChristinePereira ASK at Brunel (2014) 46 1. Enter & define variables from Variable View. • Missing • Missing data can be coded too • Chose a number not in the data, like 99 or 999 • Replace all missing values in your data with this code first
  • Dr.ChristinePereira ASK at Brunel (2014) 47 1. Enter & define variables from Variable View. • Measure • Level of Measurement (Nominal, Ordinal, Scale) • By default ALL new variables are unknown • YOU must choose the appropriate measure
  • Dr.ChristinePereira ASK at Brunel (2014) 48 2. Enter data from Data View. • Variable names • Will become column headings in Data View.
  • Dr.ChristinePereira ASK at Brunel (2014) 49 Now, let’s enter some data
  • Saving and Opening Data or Output Files Dr.ChristinePereira ASK at Brunel (2014) 50
  • Dr.ChristinePereira ASK at Brunel (2014) 51
  • Dr.ChristinePereira ASK at Brunel (2014) 52 Locate a folder to save it in: On your H drive OR On your pen drive Name it appropriately Extension .sav
  • Dr.ChristinePereira ASK at Brunel (2014) 53 Everything done in SPSS is shown here, in outline form.  Shows output for ALL analysis run in SPSS  Keeps a log of all activity of open data files  Saved with the extension .spv A data file was saved as SPSS Workshop Example.sav and logged in the output file.
  • Dr.ChristinePereira ASK at Brunel (2014) 54 New data file New output file
  • Dr.ChristinePereira ASK at Brunel (2014) 55 Existing data file Existing output file
  • Dr.ChristinePereira ASK at Brunel (2014) 56 Importing data from Excel
  • Dr.ChristinePereira ASK at Brunel (2014) 57 Click here
  • Dr.ChristinePereira ASK at Brunel (2014) 58 Click here Save this file to your H: drive or pen drive
  • Dr.ChristinePereira » Log onto Blackboard » Go to the Organisation Academic Skills » In the left column, under Workshop Presentations Click on Statistics and SPSS » Find the SPSS Workshop Download the Excel File: “CommutingSurvey.xlsx” » Save this file somewhere you can find it later. » Do not open it. You cannot import the file if it’s open. ASK at Brunel (2014) 59
  • Dr.ChristinePereira » Can be .xls OR .xlsx » Variable names CAN be imported too Must be in row 1 of the worksheet They will be imported to the Variable View » Data will appear in SPSS Data View ASK at Brunel (2014) 60
  • Dr.ChristinePereira ASK at Brunel (2014) 61 Variable names (Row 1) Filename (.xlsx) This sheet contains the dataset
  • ASK at Brunel (2014) 62 Existing data file Dr.ChristinePereira
  • Dr.ChristinePereira ASK at Brunel (2014) 63 Choose Excel file type to see your .xlsx Find the folder where you saved the fileSelect the Excel file 3 1 2
  • Dr.ChristinePereira ASK at Brunel (2014) 64 Choose the correct worksheet
  • View all data Dr.ChristinePereira ASK at Brunel (2014) 65 Variable Names (from Row 1)
  • Dr.ChristinePereira ASK at Brunel (2014) 66 This variable name from Excel could not be used. SPSS made it a label and created a new variable name
  • Dr.ChristinePereira ASK at Brunel (2014) 67 How to handle missing data
  • Dr.ChristinePereira » Any blank (i.e., missing) data is automatically considered missing by SPSS. It will not be included in the analysis. This means you DO NOT have to code missing data » Why code missing values if you don’t have to? Sometimes data accidently gets deleted. If missing values are coded then you know a blank space shouldn’t be there. There is more than one reason data is missing and you want to distinguish between them. + E.g., A participant chose not to answer a survey question or question was not applicable to them – you may want to record these as different kinds of missing data. ASK at Brunel (2014) 68
  • Dr.ChristinePereira ASK at Brunel (2014) 69 There are 3 missing values for TravelTimemin • Replace missing values with a code • Use a code that will not occur for the variable • Let’s use -1, as negative time is not possible
  • Dr.ChristinePereira ASK at Brunel (2014) 70 1
  • Dr.ChristinePereira ASK at Brunel (2014) 71 3 Select the variable you want to recode Click here to recode the variable 2
  • Dr.ChristinePereira ASK at Brunel (2014) 72 4 Enter the code as the new value Click Add. MISSING -> -1 will appear here 5 6 Click Continue then Click OK 7
  • Dr.ChristinePereira ASK at Brunel (2014) 73 Missing values have been replaced with -1 for TravelTimemin
  • Dr.ChristinePereira ASK at Brunel (2014) 74 Remember… From Variable View Define the missing values 8 • Discrete (whole numbers) • Enter missing value codes used for the variable (e.g., -1) • Click OK
  • Dr.ChristinePereira ASK at Brunel (2014) 75 This is only a code – it tells SPSS what value(s) represent missing values. It does not replace missing values with the code for you!
  • Dr.ChristinePereira » Variables go in columns » Categorical data should be coded first » If you import data from Excel, make sure to: Put variable names in the first row Code your categorical data first, then import codes » If you choose to code missing data: First, replace all missing values with the code Second, define the missing value code in the Variable View ASK at Brunel (2014) 76
  • Dr.ChristinePereira » SPSS Survival Manual, 4th Edition (2010) by Julie Pallant. » SPSS Survival Manual, 5th Edition (2013) by Julie Pallant. » Discovering Statistics Using SPSS, 3rd Edition (2009) by Andy Field. » Discovering Statistics Using SPSS, 4th Edition (2013) by Andy Field. ASK at Brunel (2014) 77
  • Dr.ChristinePereira ASK at Brunel (2014) 78