A herbal extract is claimed to lower the blood glucose level. 20 prediabetic subjects were give capsules containing lactose for 1 month and their mean blood glucose level (BGL) was measured as 127±10 mg/dl. Another sample of 20 subjects were given capsules containing dried herbal extract for one month was and the mean BGL was measured as 121±12. The question of interest was does the herbal extract result in significant BGL reduction compared to placebo. ASsuming the populations have equal standard deviation, test statistic is calculated as 0 4.318 O5.412 O4.654 3.123 O 2.745 O 1.718 O 134
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.
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