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This opens another dialog box, where you should select “Histograms” and “Show normal curve on histogram.” Once you have done this, click Continue and then OK to perform the analysis.
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You will return to the previous screen on the right-hand side of the Frequencies dialog box, click the “Charts” button. This opens another dialog box, where you should select the measures of central tendency that you require, typically, Mean, Median, Standard deviation, Variance, and Range. Untick the button “Display frequency tables.” On the right-hand side of the Frequencies dialog box, click the “Statistics” button. In the Frequencies dialog box that opens, move both variables into the Variables list box. Because you are comparing means, the data that you use must be continuous or scale data, for example, weight, height, BMI, temperature, income.Īnalyze → Descriptive Statistics → Frequencies Specifically, in our example, we test whether the Reception year children from the most deprived areas have a greater mean weight than the mean weight of all Reception year children. One Sample z-tests allow us to compare the mean of a sample with some (null) hypothesised mean of the population from which the sample is drawn in order to determine whether the sample mean differs significantly from the (null) hypothesised mean. However, the most common use of the term “ z-test” refers to the One Sample z-test, indeed this is the most commonly used variety of z-test. As with t-tests, there are many different types of tests under the category of t-test, likewise there are many different types of z-test. A “ z-test” is a generic term for any statistical test where the test statistic (usually known as the z-statistic) follows a normal distribution.