举一反三
- in comparing the means of two independent population , sample are randomly selected from normally distributed populations and population variances are equal, we can use paired t test for the mean difference.
- A researcher wants to estimate the difference in the means of two populations. A random sample of 36 items from the first population results in a sample mean of 430. A random sample of 49 items from t
- The difference between the sample mean and the population mean is called the: A: population deviation. B: population standard deviation. C: standard error of the mean. D: sampling error.
- Given an infinite population with a mean of 75 and a standard deviation of 12, the probability that the mean of a sample of 36 observations, taken at random from this population, exceeds 78 is:
- A sample of size 40 is to be taken from an infinite population whose mean and standard deviation are 68 and 12, respectively. The probability that the sample mean will be larger than 70 is:
内容
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The difference between the sample mean and the population mean is called the sampling error.
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中国大学MOOC: A population distribution is normal with a mean of 18 and standard deviation of 4. A sample of 16 observations is selected and a sample mean computed. What is the probability that the sample mean is more than 18?
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From a population of 500 elements, a sample of 225 elements is selected. It is known that the variance of the population is 900. The standard error of the mean is approximately
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Using the confidence interval when conducting a two-tail test for the population mean we do not reject the null hypothesis if the hypothesised value for µ:
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If a paired comparison test of mean differences supports rejecting the null hypothesis, then the: A: independence of the samples is statistically significant. B: standard error of the mean differences is low relative to the sample mean difference. C: difference in means is not statistically significant.