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Published byIra Young Modified over 9 years ago
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Livelihoods analysis using SPSS
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Why do we analyze livelihoods? Food security analysis aims at informing geographical and socio-economic targeting Livelihood analysis allows us to answer one of the key basic questions of food security analysis: “who are the food insecure?” This analysis also allows us to create a socio-economic profile of the vulnerable households
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How do we analyze livelihoods The standard livelihood (income) module in a CFSVA allows for a few different types of analysis We can analyze the main income activity followed by the second and third by simply running cross-tabulations with the main activity and other variables We can also use multiple response analysis to analyze all of the reported income activities (regardless of order) and run cross- tabulations We can analyze the number of income activities to see if there are significant differences between diversified households and single income households And we can identify clusters of livelihood activities which offers a more powerful form of analysis
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Types of cluster analysis available in SPSS SPSS offers three methods for cluster analysis Hierarchial clustering Two-step clustering K-means clustering
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Types of analysis available in SPSS Hierarchical clustering Uses algorithms that are agglomerative (bottom-up) or divisive (top-down) If agglomerative, each case is a cluster and then an algorithm is performed to either separate successive cases into clusters Divisive algorithms first put all cases in a single cluster and then sequentially attempt to divide them
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Types of analysis available in SPSS Two-step clustering As the name implies, clustering is done in two steps First the cases are pre-clustered into many small sub-clusters Then the sub-clusters are joined into the a specified number of clusters (SPSS can also find the number of clusters automatically)
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Types of analysis available in SPSS K-means clustering Cases are placed into a partition and then iteratively relocated into another cluster Iterations are repeated until the desired number of clusters are reached
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Issue with SPSS cluster analysis Two of the available procedures (hierarchical and k- means) require the user to know a priori the number of clusters desired Only the two-step cluster option allows for automatic determination, however, from the WFP perspective it does not produce a useful result (too few clusters) Therefore either another statistical software package needs to be used or a guess needs to be made on the number of clusters to include (and then run several iterations until a logical clustering is achieved)
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Performing cluster analysis As mentioned, there are several options available to perform cluster analysis The analyst should chose the method that they are most familiar with To give an example of one method to create the clusters, we will use the k-means method in SPSS
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Prepare the dataset It is imperative that the income activity module data is clean and without errors The sum of all activities contributions must be 100 The same activity should not be repeated for a household If an activity exists, the relative contribution must not be missing Before the clustering can be performed, the contribution of each livelihood activity must be calculated for all households To do so, syntax such as the following must be executed for all variables: compute act01 = 0. if (activity1 =1) act01 = act01+Activity1_Value. if (activity2 =1) act01 = act01+Activity2_Value. if (activity3 =1) act01 = act01+Activity3_Value. The objective of this computation is to find out for every household, what is the relative contribution of each activity to their overall livelihood After executing the syntax above for every activity, verify that the total for each household is exactly 100
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Perform the first iteration of the cluster analysis In this example, we will use the SPSS k-means method to perform cluster analysis using the contribution of each income activity as our variables of interest In SPSS select: Analyze > Classify > K-means cluster Select all of the newly created income activity variables The number of clusters is chosen at your discretion keeping in mind the number of activities listed in the survey and the knowledge that you will create a few iterations Click the ‘save’ button and chose ‘cluster membership’ Click OK or Paste
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Interpret the results SPSS will produce a few outputs (based on the options you gave) The iteration history will show you the number of iterations the change in the center of each cluster The final clusters center table is the table we look at closely Here, each variable is listed as a row and it’s average contribution to each cluster is noted in the columns Paste this table into Excel
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Interpret the results Use conditional formatting to highlight cells with a value > 10 and examine the way the clusters have attempted to group the activities
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Repeat the analysis Repeat the cluster analysis this time increasing (or decreasing) the number of clusters by 1 Examine the final clusters table again Continue to repeat this exercise until you have successfully created clusters that are logical Livelihood clusters should be able to be described in a relatively simple fashion. Usually, there is one predominant income activity defining a group and some supplemental income from other activities There is no ‘golden rule’ on the right number of clusters and some subjective but informed but decisions must be made
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Describe the clusters Once the clusters have been finalized, further examine the contribution of the activities to each cluster Write a brief description of the composition of the cluster; for example: A cluster which has a center of 78 from income from trading, selling and other commercial activity could be simply described as a ‘trader’ A cluster which has a center of 50 from cash crops and 30 from food crops could be summarized as ‘cash and food crops’ Appropriately label the final cluster variable in your dataset with the livelihood descriptions
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Explore the clusters Next, explore the livelihood clusters you’ve created Look at the frequency of the clusters in the dataset Some clusters may be combined if reasonable information allows you to do so For example, people who are ‘remittance receivers’ and ‘pensioners’ may have very similar qualities and could possibly be combined
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Analyze the clusters using cross-tabulations The livelihood clusters can be used to examine ‘who are the food insecure’ and ‘where are they’ Cross-tabulate the livelihood clusters with Food Consumption Groups (you can also compare means of the FCS between clusters) Cross-tabulate the clusters with all geographic strata Wealth and livelihood are usually highly related and should be examined Other indicators of interest: gender of household head, education of household head, etc.
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