Statistics By Jim https://statisticsbyjim.com/ Making statistics intuitive Sun, 27 Nov 2022 04:51:17 +0000 en-US hourly 1 https://wordpress.org/?v=6.1.1 https://i0.wp.com/statisticsbyjim.com/wp-content/uploads/2017/03/cropped-favicon2.png?fit=32%2C32&ssl=1 Statistics By Jim https://statisticsbyjim.com/ 32 32 Covariates: Definition & Uses https://statisticsbyjim.com/anova/covariates/ https://statisticsbyjim.com/anova/covariates/#comments Sun, 27 Nov 2022 04:51:17 +0000 https://statisticsbyjim.com/?p=18257 What is a Covariate? Covariates are continuous independent variables (or predictors) in a regression or ANOVA model. These variables can explain some of the variability in the dependent variable. That definition of covariates is simple enough. However, the usage of the term has changed over time. Consequently, analysts can have drastically different contexts in mind […]

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Weighted Average: Formula & Calculation Examples https://statisticsbyjim.com/basics/weighted-average/ https://statisticsbyjim.com/basics/weighted-average/#respond Sat, 26 Nov 2022 03:05:04 +0000 https://statisticsbyjim.com/?p=18231 What is a Weighted Average? A weighted average is a type of mean that gives differing importance to the values in a dataset. In contrast, the regular average, or arithmetic mean, gives equal weight to all observations. The weighted average is also known as the weighted mean, and I’ll use those terms interchangeably. Use a […]

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Concurrent Validity: Definition, Assessing & Examples https://statisticsbyjim.com/basics/concurrent-validity/ https://statisticsbyjim.com/basics/concurrent-validity/#respond Sat, 19 Nov 2022 02:47:14 +0000 https://statisticsbyjim.com/?p=18151 What is Concurrent Validity? Concurrent validity is the degree to which assessment scores correlate with a criterion variable when researchers measure both variables at approximately the same time (i.e., concurrently). This method validates an assessment instrument by comparing its scores to another test or variable that researchers had validated previously. The assessment is a psychological […]

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Criterion Validity: Definition, Assessing & Examples https://statisticsbyjim.com/basics/criterion-validity/ https://statisticsbyjim.com/basics/criterion-validity/#respond Tue, 15 Nov 2022 23:07:12 +0000 https://statisticsbyjim.com/?p=18082 What is Criterion Validity? Criterion validity (aka criterion related validity) is the degree to which scores from a construct assessment correlate with a manifestation of that construct in the real world (the criterion). The construct assessment is a test, measurement instrument, or psychological inventory that assesses a latent construct. Because you can’t observe the construct, […]

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Predictive Validity: Definition, Assessing & Examples https://statisticsbyjim.com/basics/predictive-validity/ https://statisticsbyjim.com/basics/predictive-validity/#respond Sat, 12 Nov 2022 21:21:30 +0000 https://statisticsbyjim.com/?p=18065 What is Predictive Validity? Predictive validity is the degree to which a test score or construct scale predicts a criterion variable measuring a future outcome, behavior, or performance. Evaluating predictive validity involves assessing the correlation between the pre-test score and the subsequent criterion outcome. Researchers frequently assess predictive validity in psychology, job performance, and academic […]

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Z Test: Uses, Formula & Examples https://statisticsbyjim.com/hypothesis-testing/z-test/ https://statisticsbyjim.com/hypothesis-testing/z-test/#respond Thu, 10 Nov 2022 05:15:21 +0000 https://statisticsbyjim.com/?p=18022 What is a Z Test? Use a Z test when you need to compare group means. Use the 1-sample analysis to determine whether a population mean is different from a hypothesized value. Or use the 2-sample version to determine whether two population means differ. A Z test is a form of inferential statistics. It uses […]

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Statistical Significance: Definition & Meaning https://statisticsbyjim.com/hypothesis-testing/statistical-significance/ https://statisticsbyjim.com/hypothesis-testing/statistical-significance/#comments Mon, 07 Nov 2022 00:29:51 +0000 https://statisticsbyjim.com/?p=17994 What is Statistical Significance? Statistical significance is the goal for most researchers analyzing data. But what does statistically significant mean? Why and when is it important to consider? How do P values fit in with statistical significance? I’ll answer all these questions in this blog post! Evaluate statistical significance when using a sample to estimate […]

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Retrospective Study: Definition & Examples https://statisticsbyjim.com/basics/retrospective-study/ https://statisticsbyjim.com/basics/retrospective-study/#comments Thu, 03 Nov 2022 04:11:00 +0000 https://statisticsbyjim.com/?p=17968 What is a Retrospective Study? A retrospective study looks back in time and assesses events that have already occurred. The researchers already know the outcome for each subject when the project starts. Instead of recording data going forward as events happen, these studies use participant recollection and data that were previously recorded for reasons not […]

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Political Polls and Their Challenges https://statisticsbyjim.com/basics/political-polls/ https://statisticsbyjim.com/basics/political-polls/#respond Sun, 30 Oct 2022 20:03:14 +0000 https://statisticsbyjim.com/?p=17942 Political polls provide crucial information during elections. When done correctly, small samples can predict the outcomes. We’re approaching election time here in the U.S., and campaigns are switching into high gear along with political polls! You’d think that conducting a poll is straightforward. You ask a bunch of people who they’ll vote for and count […]

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Survivorship Bias: Definition, Examples & Avoiding https://statisticsbyjim.com/basics/survivorship-bias/ https://statisticsbyjim.com/basics/survivorship-bias/#comments Sun, 30 Oct 2022 04:20:42 +0000 https://statisticsbyjim.com/?p=17924 What is Survivorship Bias? Survivorship bias, or survivor bias, occurs when you tend to assess successful outcomes and disregard failures. This sampling bias paints a rosier picture of reality than is warranted by skewing the mean results upward. Survivorship bias is a sneaky problem that tends to slip into analyses unnoticed. For starters, it feels […]

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