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Ricavita0118's avatar
Ricavita0118
Copper Contributor
May 13, 2020
Solved

request to solve a formula to find the weight of pigs at different days of during an experiment

hello,

i attache the file with the problem i would like to solve:

 

in a experiment we measured the weight of pigs after weaning.

in the experiment there are 2 groups, group A (normal diet + product A), and group control (normal diet).

we measured the animals at the day0 (entering the experiment) , then at day 7, 14, and 35.

we do not have the weights in the other days of the experiment, and i would like to find the formula that helps me to estimate the weights in those days and fill the table with the empty cells.

thank you so much to whoever is able to help.

thank you.

  • SergeiBaklan's avatar
    SergeiBaklan
    May 13, 2020

    Ricavita0118 

    If use polynomic approximation we may find coefficients with LINEST() function. For such one

     formula for first curve coeficients is

    =LINEST(C4:F4,$C$7:$F$7^{1;2;3},TRUE,FALSE)

    If your Excel doesn't support Dynamic Arrays enter it as array formula (Ctrl+Shift+Enter)

4 Replies

    • Ricavita0118's avatar
      Ricavita0118
      Copper Contributor

      AshaKantaSharma thank you for your help.

      unfortunately the average seems do not work because if we use the linear trend line does have a R2 very low.

      I've tried to use the polynomial equation (degree 2) formula but i'm not able to solve it..

      the R2 obtained with the polynomial trend line seems to be closer to the real situation, but i'm not able to solve it.

       

      the equation of one curve is 

      y = 2.1482x2 - 6.7453x + 12.323
      R² = 0.9793

      and the other is 

      y = 2.0975x2 - 6.8495x + 12.469
      R² = 0.9787

       

      is it the right direction i am following or i am totally wrong?

      thanks  a lot

       

       

      • SergeiBaklan's avatar
        SergeiBaklan
        Diamond Contributor

        Ricavita0118 

        If use polynomic approximation we may find coefficients with LINEST() function. For such one

         formula for first curve coeficients is

        =LINEST(C4:F4,$C$7:$F$7^{1;2;3},TRUE,FALSE)

        If your Excel doesn't support Dynamic Arrays enter it as array formula (Ctrl+Shift+Enter)

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