Write that down.you are about to be asked to evaluate bias. An unbiased estimator is as likely to overestimate as it is to underestimate, whereas a biased estimator will tend toĬonsistently overestimate, or consistently underestimate. Of critical importance to obtaining accuracy in our estimates is the use of When making estimates, we are far more concerned with accuracy (proximity to the actual value) than we are with precision Thus, the preceding formula can be read as "the sample mean is an estimate of the The population mean is represented by the symbol μ (lower case Mu in the Greek alphabet), and the caret (^) over the Is the sample mean, and it is an estimate, based on our sample, of the actual mean of the statistical population. In this case a subscript for the Y would indicate a particularĮ.g., ∑Y control would indicate the sum of all the observations for the control group. ∑Y is the notation that we will use for the sum of all the ForĮxample, Y 4 would indicate the 4th observation. We wish to identify a specific observation, we will use a subscript. The total number of observations, i.e., the sample size, will be denoted as n. We will use Y to denote the value of an observation. Reason, we will use the formula for calculation of the sample mean to indicate some of the notation that we will be using ![]() The mean simply is the arithmetic average of the observations, and is a summary statistic that we all are familiar with. Measures of central tendency are mean, median, and mode. Measured) is summarized by reference to some value associated with the approximate center of the distribution. ![]() Where a particular distribution of data is located on the X-axis (which represents the values of the variable being Central Tendency (Chapter 3 in Zar, 2010) The shape of the distribution, specifically the degree of symmetry, will also be important to describe. X-axis (the value of the variable being measured), whereas measures of dispersion describe how spread out the observations are along the X-axis. Measures of central tendency essentially describe the position of the distribution on the Information that need to be provided for any distribution are the central tendency of the distribution, and theĭispersion of the distribution. Provide a means of summarizing the information contained within a frequency distribution. The purpose of descriptive statistics is to ![]() Only on rare occasions do we present the raw data. Descriptive Statistics Descriptive StatisticsĪs mentioned previously, a frequency distribution contains all of the observations for a particular sample, which we refer
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