Eating Paint
Stat-403/ 650/ 890 (BPK) – Assignment 1 2013 Spring Term
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Question 1. Eating paint It has been estimated that lead poisoning resulting from an unnatural craving (pica) for substances such as paint may affect as many as a quarter of a million children each year, causing them severe, irreversible retardation. Explanations for why children voluntarily consume lead range from “improper parental supervision” to “a child’s need to mouth objects.” Some researchers, however, have been investigating whether the habit of eating such substances has a nutritional explanation. One such study involved a comparison of a regular diet and a calciumdeficient diet on the ingestion of a lead acetate solution on rats. Each rat in a group of 20 was randomly assigned to either an experimental or a control group. Those in the control group received a normal diet, while those in the experimental group received a calcium deficient diet. Each of the rats occupied a separate cage and was monitored to observe the amount of a 0.15% lead-acetate solution consumed during the study period (ml). Here is the data: Control: Exper : 5.4 6.8 6.2 7.5 3.1 8.6 3.8 7.6 6.5 5.5 5.8 4.9 6.4 5.4 4.5 4.5 4.9 8.5 4.0 6.3
1. Carefully describe how to randomize in this experiment and draw an possible experimental plan, i.e. show which rat is randomized to which trial, which rat is assigned to which cage, etc. You could present a table similar to: Cage: Rat : Treatment: 1 2 c 2 10 e 3 12 e 4 ..... 14 ..... e .....
2. Construct side-by-side dot and box plots. What do the graphs seem to indicate?
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3. Find the simple summary statistics for each group. Find a standard error for each mean, and a confidence interval for the mean of each group. Interpret the se’s and the confidence intervals. 4. Estimate the difference in the means and obtain an estimated se for the difference and a confidence interval for the difference. Interpret the se and the confidence interval. 5. Define the parameters of this experiment,
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Question 1. Eating paint It has been estimated that lead poisoning resulting from an unnatural craving (pica) for substances such as paint may affect as many as a quarter of a million children each year, causing them severe, irreversible retardation. Explanations for why children voluntarily consume lead range from “improper parental supervision” to “a child’s need to mouth objects.” Some researchers, however, have been investigating whether the habit of eating such substances has a nutritional explanation. One such study involved a comparison of a regular diet and a calciumdeficient diet on the ingestion of a lead acetate solution on rats. Each rat in a group of 20 was randomly assigned to either an experimental or a control group. Those in the control group received a normal diet, while those in the experimental group received a calcium deficient diet. Each of the rats occupied a separate cage and was monitored to observe the amount of a 0.15% lead-acetate solution consumed during the study period (ml). Here is the data: Control: Exper : 5.4 6.8 6.2 7.5 3.1 8.6 3.8 7.6 6.5 5.5 5.8 4.9 6.4 5.4 4.5 4.5 4.9 8.5 4.0 6.3
1. Carefully describe how to randomize in this experiment and draw an possible experimental plan, i.e. show which rat is randomized to which trial, which rat is assigned to which cage, etc. You could present a table similar to: Cage: Rat : Treatment: 1 2 c 2 10 e 3 12 e 4 ..... 14 ..... e .....
2. Construct side-by-side dot and box plots. What do the graphs seem to indicate?
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3. Find the simple summary statistics for each group. Find a standard error for each mean, and a confidence interval for the mean of each group. Interpret the se’s and the confidence intervals. 4. Estimate the difference in the means and obtain an estimated se for the difference and a confidence interval for the difference. Interpret the se and the confidence interval. 5. Define the parameters of this experiment,