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# 3.5.3 Pharmacology I ### Lab 7 Evaluation of muscle relaxation action of Diazepam using Rotarod (Con't...d)

There are two possible error in this type of experiments like clinical trial: type I error and type II error.
Before, explaining the eror we need to define the null hypothesis' and alternate hypothesis'.

#### Null hypothesis

The possibility of the difference of mean of two group to be zero.

#### Alternate hypothesis

The possibility of the mean difference other than zero.

#### Type I error

When we find the null hypothesis false but actually it is true, then the error is defined as type I error ($/alpha$).

#### Type II error

When we find a null hypothesis but it is incorrect.

##### Type I error calculation

The mean of a data points $x$ as $\bar{x}=\sum{x/n}$. The variance could be calculated as $\sigma^2=\sum(x-\bar{x})^2/(n-1)$. Where $\sigma$ is the standerd deviation of the data point.

##### Reference range of individuals:

95% of the samples should lie between $Mean \pm 1.96 \times \sigma$ ranges.

Standard error of mean SE = $\sigma/ \sqrt{n}$

Standard error of a proportion or percentage =$\sqrt{P(100-P)/n}$

SE of differences between two mean $SE_{diff} = \sqrt{\sigma^2_1/n_1 +\sigma^2_2/n_2}$

##### P value:

It is the probability of obtaining the null hypothesis true. It must be $<0.05$ when the $n$ is 6-20 and $<.001$ when n is 100. If the P value is $<0.05$, we can reject the null hypothesis and there is $(100-0.05 \times 100)$ or 95% chance of the result to be significant.

If the /emph{P} value is $>0.05$, we can say that there is insufficient data to reject the null hypothesis and the result is insignificant.