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Effect of Organic Soybeans after 5 Days After 5 days, the proportion of fruit flies eating organic soybeans still alive is \(0.90,\) while the proportion still alive eating conventional soybeans is 0.84 . The standard error for the difference in proportions is 0.021 .

Short Answer

Expert verified
The 95% confidence interval for the difference in fruit fly survival rates between organic and conventional soybeans is \(0.01884\) to \(0.10116\). Since this does not include 0, there is a statistically significant difference suggesting that the survival rate is higher for fruit flies consuming organic soybeans.

Step by step solution

01

Identifying the information

Two pieces of raw information are provided in the problem: the proportion of fruit flies alive after eating organic and conventional soybeans, \(0.90\) and \(0.84\) respectively, and the standard error for this difference, \(0.021\). The goal is to calculate the confidence interval.
02

Calculate the difference in proportions

From the data, subtract the proportion of fruit flies that survived after eating conventional soybeans from the proportion that survived after eating organic soybeans. Which results in \(0.90 - 0.84 = 0.06\). This is the difference in proportions.
03

Determine the confidence interval

We can make use of the standard error to create a 95% confidence interval. Generally, this interval is calculated as \((Difference \pm (1.96 * SE))\) where SE stands for standard error. We substitute in the values to get \((0.06 \pm (1.96 * 0.021))\). After calculations, this interval is \((0.06 \pm 0.04116)\) or from \(0.01884\) to \(0.10116\).
04

Interpret results

Since this interval does not include 0, we can infer that the difference between the two proportions is statistically significant. The likelihood of survival of fruit flies is higher when consuming organic soybeans rather than conventional ones.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Confidence Interval
Understanding the confidence interval is crucial when dealing with statistics. It provides a range of values that we are fairly sure our true parameter lies within. In the problem, the calculation of the confidence interval is based on the difference in proportions of the survival rates of fruit flies eating different types of soybeans.

To calculate this interval, we use the standard error, which in this case is 0.021, and a z-score that corresponds to our confidence level. For a 95% confidence interval, the z-score is commonly 1.96. The formula becomes the difference in proportions plus or minus 1.96 times the standard error. The resulting confidence interval in our exercise, from 0.01884 to 0.10116, tells us that with 95% certainty, the true difference in survival rates between the two groups falls within these two values.

This interval is particularly helpful when trying to understand the effect of organic versus conventional soybeans on fruit fly survival—with the given data suggesting a positive effect for the organic variant.
Standard Error
The standard error (SE) measures the precision with which we can estimate the difference between two sample proportions. It takes into account both the sample size and the variability within the data.

In the context of our exercise, the SE of 0.021 indicates the variability in the estimation of the difference in survival rates—is it a small or large variance? Since lower SE values indicate more precision, this relatively small standard error of 0.021 implies our estimate of the 0.06 difference in proportions is quite precise.

When calculating the confidence interval, the SE is multiplied by a z-score (1.96 for 95% confidence) to adjust the margin of error for the estimated difference, allowing us to quantify our certainty about where the true difference likely falls.
Statistical Significance
Statistical significance is a determination of whether the observed difference between groups is due to chance or a specific cause. In this case, we are considering if the difference in survival rates between fruit flies that ate organic versus conventional soybeans is significant.

When calculating the confidence interval, we look to see if zero falls within this range. Since our interval is between 0.01884 to 0.10116 and does not include zero, we conclude that the difference is likely not due to random chance—there is statistical significance. In simpler terms, the fruit flies' increased survival rate when eating organic soybeans is not a fluke; there's a real effect happening, discernible from the data.
Proportion
A proportion is simply a part, share, or number considered in comparative relation to a whole. In our scenario, we're dealing with the proportion of fruit flies that survived after eating two types of soybeans.

The given proportions—0.90 for organic and 0.84 for conventional—help us understand the relative effectiveness of each food source on the health of the fruit flies. By comparing these proportions, we're able to assess the impact of different conditions on a population. In studying the difference in proportions, which turns out to be 0.06, we get a clearer picture of the advantage (if any) that organic soybeans have over conventional ones for fruit fly survival.

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