# Null hypothesis: μ = 72 Alternative hypothesis: μ ≠72

An appropriate hypothesis/prediction from BIO 325L Write the prediction of the above.
AP Biology Lab 7 Name: _____ Genetics of Organisms Write a null hypothesis that describes the mode of inheritance of the trait you studied.

## Null hypothesis: μ = 72 Alternative hypothesis: μ ≠72

### Null hypotheses regarding the distribution of genetic variation.

The p-value is p = 0.236. This is not below the .05 standard, so we do not reject the null hypothesis. Thus it is possible that the true value of the population mean is 72. The 95% confidence interval suggests the mean could be anywhere between 67.78 and 73.06.

### What is a null hypothesis and how is it useful?

The level of statistical significance is often expressed as the so-called p-value. Depending on the statistical test you have chosen, you will calculate a probability (i.e., the p-value) of observing your sample results (or more extreme) given that the null hypothesis is true. Another way of phrasing this is to consider the probability that a difference in a mean score (or other statistic) could have arisen based on the assumption that there really is no difference. Let us consider this statement with respect to our example where we are interested in the difference in mean exam performance between two different teaching methods. If there really is no difference between the two teaching methods in the population (i.e., given that the null hypothesis is true), how likely would it be to see a difference in the mean exam performance between the two teaching methods as large as (or larger than) that which has been observed in your sample?

## Choose the correct null and alternative hypotheses below A ..

where k is the number of comparison groups and N is the total number of observations in the analysis. If the null hypothesis is true, the between treatment variation (numerator) will not exceed the residual or error variation (denominator) and the F statistic will small. If the null hypothesis is false, then the F statistic will be large. The rejection region for the F test is always in the upper (right-hand) tail of the distribution as shown below.

## Null and Alternative Hypothesis | Real Statistics Using …

Solution First, we write write down the null and alternative hypothesesThis is a lefttailed test. The -score that corresponds to is . The critical region is the areathat lies to the left of . If thez-value is less than there we will reject thenull hypothesis and accept the alternative hypothesis. If it is greaterthan , we will fail to reject the nullhypothesis and say that the test was not statistically significant.Wehave There is another way to interpret the test statistic.

### How to write the null and alternative hypothesis

So, you might get a p-value such as 0.03 (i.e., p = .03). This means that there is a 3% chance of finding a difference as large as (or larger than) the one in your study given that the null hypothesis is true. However, you want to know whether this is "statistically significant". Typically, if there was a 5% or less chance (5 times in 100 or less) that the difference in the mean exam performance between the two teaching methods (or whatever statistic you are using) is as different as observed given the null hypothesis is true, you would reject the null hypothesis and accept the alternative hypothesis. Alternately, if the chance was greater than 5% (5 times in 100 or more), you would fail to reject the null hypothesis and would not accept the alternative hypothesis. As such, in this example where p = .03, we would reject the null hypothesis and accept the alternative hypothesis. We reject it because at a significance level of 0.03 (i.e., less than a 5% chance), the result we obtained could happen too frequently for us to be confident that it was the two teaching methods that had an effect on exam performance.

### How to choose the null and alternative hypothesis

Depending on how you want to "summarize" the exam performances will determine how you might want to write a more specific null and alternative hypothesis. For example, you could compare the mean exam performance of each group (i.e., the "seminar" group and the "lectures-only" group). This is what we will demonstrate here, but other options include comparing the distributions, medians, amongst other things. As such, we can state:

### Writing Null and Alternative Hypotheses - YouTube

When considering whether we reject the null hypothesis and accept the alternative hypothesis, we need to consider the direction of the alternative hypothesis statement. For example, the alternative hypothesis that was stated earlier is: