5. The mean length hospital stay for children treated for pneumonia was compared between 2014 and 2004. In 2014 (population 1), 21 children were sampled and in 2004 (population 2) another sample of 21 was taken. Results for many test are shown in the table. Do the data indicate that the mean hospital stay for children has decreased? Test with a significance level of 5%. 2014 2004 Sample mean Sample standard deviation 3.7 4.3 1.5 1.2 Sample size 21 21
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.
Given
The data of mean length hospital stay for children for pneumonia in 2004 and 2014 is shown below
The level of significance is 5% or 0.05.
Let be the mean length hospital stay for children in 2014 and 2004.
The null and alternate hypothesis are shown below
The test statistic is calculated as shown below
The degree of freedom is calculated using the below mentioned formula
Thus we use degree of freedom as 38
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