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  • Compare percentage across different tables

    Hey

    I want to compare percentages across tables. So, for example I want to test if investor_A invest more in the seed stage of a startup than investor_B. I could do it with dummys for the funding type and a ttest but is there a better way in stata?


    Code:
    . tab fundingtype if investor_A == 1
     
                Funding Type |      Freq.     Percent  
    -------------------------+-----------------------------------
                        Seed |      1,230       65.15      
                    Series A |        461       24.42      
                    Series B |        197       10.43  
     -------------------------+-----------------------------------
                       Total |      1,888      100.00
     
     
    . tab fundingtype if investor_B == 1
     
                Funding Type |      Freq.     Percent  
    -------------------------+-----------------------------------
                        Seed |      1,030       62.43      
                    Series A |        300       18.18      
                    Series B |        320       19.39  
     -------------------------+-----------------------------------
                       Total |      1,650      100.00
    Kind regards
    Alex

  • #2
    I think your problem statement can be formulated as two different questions, and which you choose if best for you to decide. I'm making an assumption that investors are not seeding the same companies and therefore the underlying data from investors are independent of each other.

    If all you have is funding type, then a simple test of two-independent proportions is possible by collapsing the other categories that are of interest (i.e., Series A and B). The command you could use is called -prtest- or its immediate form if you want to plug in the numbers directly, -prtesti-. (These commands exploit large-sample statistics, which your data will satisfy here.) This would only tell you if their frequency of funding is different, without regard to the amount invested.

    If the amount of money invested is important, then a t-test (or a non-parametric alternative) would be another way to go. These commands are -ttest- and -ttesti-.

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