A study was conducted to assess the effects that occur when children are exposed to cocaine before birth. Children were tested at age 4 for object assembly skill, which was described as "a task requiring visual-spatial skills related to mathematical competence." The 188 children born to cocaine users had a mean of 7.2 and a standard deviation of 3.1. The 183 children not exposed to cocaine had a mean score of 8.1 with a standard deviation of 2.9. Assume that the two samples are independent simple random samples selected from normally distributed populations, and do not assume that the population standard deviations are equal. Let population 1 be children born to cocaine users. Complete parts (a) and (b) below Use a 0.01 significance level to test the claim that prenatal cocaine exposure is associated with lower scores of four-year-old children on the test of object assembly. Identify the null and alternative hypotheses. The test statistic is State the conclusion for the test.
Inverse Normal Distribution
The method used for finding the corresponding z-critical value in a normal distribution using the known probability is said to be an inverse normal distribution. The inverse normal distribution is a continuous probability distribution with a family of two parameters.
Mean, Median, Mode
It is a descriptive summary of a data set. It can be defined by using some of the measures. The central tendencies do not provide information regarding individual data from the dataset. However, they give a summary of the data set. The central tendency or measure of central tendency is a central or typical value for a probability distribution.
Z-Scores
A z-score is a unit of measurement used in statistics to describe the position of a raw score in terms of its distance from the mean, measured with reference to standard deviation from the mean. Z-scores are useful in statistics because they allow comparison between two scores that belong to different normal distributions.
A study was conducted to assess the effects that occur when children are exposed to cocaine before birth. Children were tested at age 4 for object assembly skill, which was described as "a task requiring visual-spatial skills related to mathematical competence." The 188 children born to cocaine users had a mean of 7.2 and a standard deviation of 3.1. The 183 children not exposed to cocaine had a mean score of 8.1 with a standard deviation of 2.9. Assume that the two samples are independent simple random samples selected from
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