Could you help with this question? I think data needs transformation when i run levene.test, non constant variance fails. Not sure what transformation works for this model

nit_level

We wish to study the competition of grass species in particular, big bluestem (from the tall grass prairie) versus quack grass (a weed). We set up an experimental garden with 24 plots. These plots were randomly al- located to the six treatnments nitrogen level 1 (200 mg N/kg soil) and no mg N/kg soil and no irrigation, nitrogen level 3 (600 mg N/kg soil) no ir- level 4 and 1 cm/week irigation. Big bluestem was seeded in these plots and allowed to establish itself. After one year, we added a measured amount of quack grass seed to each plot. After another year, we harvest the grass and measure the fraction of living material in each plot that is big bluestem. We wish to determine the effects if any) of nitrogen and/or irrigation on the ability of quack grass to invade big bluestem. (Based on Wedin 1990.) N level 1 2 3 4 4 97 83 85 64 52 48 96 87 84 72 56 58 92 78 78 63 44 49 95 81 79 74 50 53 (a) Do the data need a transformation? If so, which transformation? (b) Provide an Analysis of Variance for these data. Are all the treatments equivalent? (c) Are there significant quadratic effects of nitrogen under noninrigated conditions (d) Is there a si gnificant effect of irigation (e) Under which conditions is big bluestem best able to prevent the inva sion by quack grass? Is the response at this set of conditions signifi- cantly different from the other conditions? We wish to study the competition of grass species in particular, big bluestem (from the tall grass prairie) versus quack grass (a weed). We set up an experimental garden with 24 plots. These plots were randomly al- located to the six treatnments nitrogen level 1 (200 mg N/kg soil) and no mg N/kg soil and no irrigation, nitrogen level 3 (600 mg N/kg soil) no ir- level 4 and 1 cm/week irigation. Big bluestem was seeded in these plots and allowed to establish itself. After one year, we added a measured amount of quack grass seed to each plot. After another year, we harvest the grass and measure the fraction of living material in each plot that is big bluestem. We wish to determine the effects if any) of nitrogen and/or irrigation on the ability of quack grass to invade big bluestem. (Based on Wedin 1990.) N level 1 2 3 4 4 97 83 85 64 52 48 96 87 84 72 56 58 92 78 78 63 44 49 95 81 79 74 50 53 (a) Do the data need a transformation? If so, which transformation? (b) Provide an Analysis of Variance for these data. Are all the treatments equivalent? (c) Are there significant quadratic effects of nitrogen under noninrigated conditions (d) Is there a si gnificant effect of irigation (e) Under which conditions is big bluestem best able to prevent the inva sion by quack grass? Is the response at this set of conditions signifi- cantly different from the other conditions