Activity 2: Diet Cola and Calcium Does diet cola wash calcium out of our systems

Question

Activity 2: Diet Cola and Calcium Does diet cola wash calcium out of our systems? A study to investigate this question randomly assigned 16 healthy women to drink 24 ounces of either diet cola or water. Their urine was collected for three hours after ingestion and calcium excretion was measured. For the 8 diet cola drinkers, mean amount of calcium excreted was 56.0 mg with a standard deviation of 4.93 mg. For the 8 water drinkers, the mean was 49.1 mg with a standard deviation of 3.64 mg. Neither sample had any significant outliers or skewness. In this activity we will calculate and interpret a 95% confidence interval for the difference in mean amount of calcium excreted between diet cola drinkers (group 1) and water drinkers (group 2) Why is it important that neither sample had any significant outliers or skewness? Fill in the table: n1 s1 x _1 n2 s2 x _2 What is the correct df to use for finding the t* value? Find the correct t*. Set up the calculation for the SE. You do not need to complete the calculations. Assuming the SE is 2.17, find the 95% confidence interval. Interpret the interval in context. Does diet cola appear to affect how much calcium is washed out of the drinker’s system?

Explanation / Answer

Why is it important that neither sample had any significant outliers or skewness?

Because that will inflate the varaince of the sample which is not counted as good sample and the assumptions of normality of sample is unjustified.

Here let say diet cola drinkers are 1 and water drinkers are 2

so x1 = 56 mg and s1 = 4.93 mg ; n1 = 8

x2= 49.1 mg and s2 = 3.64 mg ;n2 = 8

Here SE = 2.17

95% confidence interval = (x1 - x2 ) +- tdF,a * SE

= (56.0 - 49.1) +- t14,0.05 * 2.17

= 6.9 +- 2.1448 * 2.17

= (2.2458, 11.5442)

so the confidence interval doesn't consist the value of Zero so yes, diet cola appear to affectcalcium is washed out of the drinker’s system.

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