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I have a model equation with 10 year and 10 industry dummies. In equation, it will look like this: year$_1$ year$_2$ ... year$_10$ ind$_1$ ind$_2$ .... ind$_{10}$ which is too long to write out. Is there any other way I can write it? maybe with summation notation?

Lev = β0 + β1 PROF + β2 SIZE + β3 TANG + β4GROWTH +β5 LIQ +β6 year1 + β7 year2+ β8 year3 +β9year4 +β10 year5 +β11year6 +β12year7 +β13year8 +β14year9 +β15year10 +β16ind1 +β17ind2 +β18ind3 +β19ind4 +β20 ind5 +β21ind6 +β22ind7 +β23ind8 +β24ind9 +β25ind10

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closed as unclear what you're asking by Nick Cox, kjetil b halvorsen, mdewey, Tim Feb 18 at 12:41

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ If people expect to see each coefficient, then that's what's expected, and not otherwise. Not clear to me what else you're asking, as there's some unstated context of assignment/thesis or dissertation/paper for journal that influences or determines what's expected. $\endgroup$ – Nick Cox Feb 18 at 9:17
  • $\begingroup$ Lev = β0 + β1 PROF + β2 SIZE + β3 TANG + β4GROWTH +β5 LIQ +β6 year1 + β7 year2+ β8 year3 +β9year4 +β10 year5 +β11year6 +β12year7 +β13year8 +β14year9 +β15year10 +β16ind1 +β12ind2 +β13ind3 +β14ind4 +β15 ind5 +β16ind6 +β17ind7 +β18ind8 +β19ind9 +β20ind10 Ths equation is quite long, so I would like to know how can I show it in a simpler form if possible $\endgroup$ – Winter T Feb 18 at 9:22
  • $\begingroup$ Maybe a plot would be nicer. $\endgroup$ – user2974951 Feb 18 at 9:51
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    $\begingroup$ Still, no context. Just possibly, you might be expected to be explicit to show your understanding. As $\beta_{12}$ to $\beta_{16}$ appear twice here, that might be a little shaky. OTOH, no one is much interested in notation being defined if it is never used thereafter. $\endgroup$ – Nick Cox Feb 18 at 11:19
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What I have seen in some papers is that people simply add a vector of variables so that they don't have to write them out. In your case that would look something like this

Lev = β0 + β1 PROF + β2 SIZE + β3 TANG + β4GROWTH +β5 LIQ + X'β + e

And then below the equation you explain that X is a vector of year and industry dummy variables.

Though not clear from your question, just in case I wanted to point out that you cannot add 10 year dummies and 10 industry dummies if you only have 10 years and 10 industries in your sample. Doing so would induce perfect multicollinearity.

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  • $\begingroup$ Yes you understood my question. Thanks for the suggestion, yes I have base group for my dummies. My sample has 11 years and 11industries. $\endgroup$ – Winter T Feb 18 at 13:43

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