C431 Healthcare Research & Statistics Topic 2 with 100% correct answers

Mean Is the average of the spread of the data; is the sum of all the values, divided by the number of values. Median Is the midpoint/half of the spread of data value. Mode Is the value of data that occurs most frequently. Standard Deviation The measure of variability. Also represented by the Greek letter sigma. Is a measure that is used to quantify the amount of variation or dispersion of a set of data values. "Thin" curves means you remain close to the mean average. "Fat" curve means data is wider spread. Normal Distribution Curve A symmetrical, bell-shaped curve that describes the distribution of many types of data; A set of data with a single center point that represents the mean, median, and mode whose values are equally distributed to both sides. Null Hypothesis The hypothesis that there is no significant difference between specified populations, any observed difference being due to sampling or experimental error. Is generally the current state that you are trying to disprove. Normally states No relationship or No difference. ("Status Quo") p-value (probability value) This is used when we wish to see how likely it is that a hypothesis is true. A low value indicates the results are very unlikely if the null hypothesis were true which leads to rejecting the null. Threshold of alpha = 0.05. If the results are less than 5% likely by chance then we believe we found a difference or relationship worth noting. Two-Tailed Tests Hypothesis testing in which both ends of the sampling distribution are used to define the region of improbable values. Looking at both sides of the curve; comparing the relationship/difference in both directions. One-Tailed Tests A hypothesis test in which rejection of the null hypothesis occurs for values of the test statistic in one sampling of its distribution. Only looking at one side of the curve; only trying to prove a difference in one direction. Confidence Intervals Are typically used when, instead of simply wanting the mean value of a sample, we want a range that is likely to contain the true population value. The range in which the true parameter can be found within a given percentage of likelihood. Most frequently used value is 95%. This tells us that 95% of the time, the test statistic will fall within the given range. T-tests A significance test used to compare the means (average) of two groups/samples to see if they are the same. Keywords: differences, compare Analysis of Variance (ANOVA) This is a group of statistical techniques used to compare the means of three or more groups/samples to see if they are roughly the same -- the "null hypothesis." Keywords: difference, compare Chi-Squared It is a measure of the difference between actual and expected frequencies. Also tests for independence and dependence between two variables. Correlation This is where there is a significant relationship between two variables. Keywords: relationship, association Descriptive Statistics Are used to describe the basic features of the data in a study. They provide simple summaries about the sample and the measure. Together with simple graphics analysis, they form the basis of virtually every quantitative analysis of data. Bar Charts Compare data among categories. Looks at categorical data. X-axis represents the categories. Y-axis represents the counts/frequencies. Line Graph Compare data over time. Displays data that changes over time. Shows trends. Makes predictions. Compares two or more variables over time. Dot Plot A graphical device that summarizes data by the number of dots above each data value on the horizontal axis. Pie Chart Composition of data among categories. Illustrates numerical portion. Each slice is relative to the size of a particular category in a given whole group. Shows percentage or proportional data. Box and Whiskers Plot (Box Plot) Shows the distribution of data along a number line. Shows the shape of a distribution and the presence of outliers. Reports the distribution that are non-normal in shape. Displayed vertically or horizontally. Graph the 5 number summary. Histogram Is a graphical display of data using bars of different heights. Each bar groups numbers into ranges. Taller bars show that more data falls in that range. Displays the shape and spread of continuous sample of data. Scatterplot A graph in which the values of two variables are plotted along the axes, the pattern of the resulting points revealing any correlation present. Inferential Statistics Numerical data that allow one to generalize- to infer from sample data the probability of something being true of a population. You are trying to reach conclusions that extend beyond the immediate data alone.