Very Short Guide to Stats for SGR Basics of aggregate and statistical data

Inferential v. Descriptive Descriptive statistics “describe” the data of a sample or population. They are usually aggregate data Descriptive statistics “describe” the data of a sample or population. They are usually aggregate data Average (Mean) GPA Average (Mean) GPA Standard Deviation of SAT score Standard Deviation of SAT score Inferential statistics “infer” (i.e. conclude) relationships between a sample AND a population, or “infer” past, present or future results of a sample/population based on its data. Inferential statistics “infer” (i.e. conclude) relationships between a sample AND a population, or “infer” past, present or future results of a sample/population based on its data. Regression/correlation analysis of GPA and SAT (relationship between SAT and GPA, and SAT can be used to predict GPA) Regression/correlation analysis of GPA and SAT (relationship between SAT and GPA, and SAT can be used to predict GPA)

Population v. Sample In inferential statistics, you would refer to the number of participants in your survey as N. If it is a sample or part of a whole, it is n (lowercase), and if it is a total population, it is N (uppercase). In inferential statistics, you would refer to the number of participants in your survey as N. If it is a sample or part of a whole, it is n (lowercase), and if it is a total population, it is N (uppercase). Population: N = 4,432 Population: N = 4,432 Sample: n = 100 Sample: n = 100 In descriptive studies and descriptive statistics, it is common to refer to participants as N, subgroups of those participants as n In descriptive studies and descriptive statistics, it is common to refer to participants as N, subgroups of those participants as n Of the total students surveyed (N = 100), only 10% (n = 10) were male. Of the total students surveyed (N = 100), only 10% (n = 10) were male. For the SGR, you would refer to then the participants as N since this is a descriptive study. For the SGR, you would refer to then the participants as N since this is a descriptive study.

Descriptive Stats 101 Central Tendency measures common “middles” Central Tendency measures common “middles” Mean is the arithmetic average of items or values Mean is the arithmetic average of items or values Mode is the most occurring item or value Mode is the most occurring item or value Median is the item or value of which 50% are greater and 50% are less. Median is the item or value of which 50% are greater and 50% are less. Sometimes GPA or time can be used as a measure, but another measure is one of attitudes and beliefs using a Likert-type scale. Sometimes GPA or time can be used as a measure, but another measure is one of attitudes and beliefs using a Likert-type scale. Standard Deviation is a measure of the spread of items or values in a series. Understanding the variation can help you see how close a particular item or value is to other numbers. Standard Deviation is a measure of the spread of items or values in a series. Understanding the variation can help you see how close a particular item or value is to other numbers. Distribution (Histogram) is a visual representation of the number of a particular result in an array of numbers. Distribution (Histogram) is a visual representation of the number of a particular result in an array of numbers. In this series (number of hours I played WoW over break): 8, 0, 0, 3, 2, 10, 0 Mean = 3.29, Mode = 0, Median = 2, SD = 4.11 Mean = 3.29, Mode = 0, Median = 2, SD = 4.11 In this series (number of hours I worked this week): 8, 8, 8, 8, 6, 6, 5 Mean = 7, Mode = 8, Median = 8, SD = 1.29 Mean = 7, Mode = 8, Median = 8, SD = 1.29

Using Excel to do your stats Mean { =average(range) } Mean { =average(range) } You can compute mode { =mode(range) } or median {=median(range) }, but they might not be as useful in this project. You can compute mode { =mode(range) } or median {=median(range) }, but they might not be as useful in this project. Standard Deviation { =stdev(range) } Standard Deviation { =stdev(range) } You can also count the number of instances of a value including instances of text: { =countif(range,”value”) } You can also count the number of instances of a value including instances of text: { =countif(range,”value”) } The following example would count every instance of “male” in the range: The following example would count every instance of “male” in the range: =countif(A2:A7,”male”) =countif(A2:A7,”male”) You can create frequency distribution histograms by using Tools -> Data Analysis, then Historgram. Histograms count the number of instances of a result in a given array. You can create frequency distribution histograms by using Tools -> Data Analysis, then Historgram. Histograms count the number of instances of a result in a given array. You can also find these commands by using Insert -> Function. There are also far more complex inferential statistics available in Excel You can also find these commands by using Insert -> Function. There are also far more complex inferential statistics available in Excel You can do a complete Descriptive Stats Summary by selecting Tools > Data Analysis (If you don’t see a Data Analysis, then (Excel 2003) Tools > Add-ins > Analysis ToolPak; (Excel 2007) Excel Options > Add-ins > Manage Add-ins > Analysis ToolPak You can do a complete Descriptive Stats Summary by selecting Tools > Data Analysis (If you don’t see a Data Analysis, then (Excel 2003) Tools > Add-ins > Analysis ToolPak; (Excel 2007) Excel Options > Add-ins > Manage Add-ins > Analysis ToolPak

Writing Stats in APA Standard Deviation = SD Standard Deviation = SD Mean = M Mean = M Descriptive statistics are often written in parentheses after an item that the statistic refers to, and symbols and numbers should be separated by a space Descriptive statistics are often written in parentheses after an item that the statistic refers to, and symbols and numbers should be separated by a space In a survey of DU students, participants (N = 100) responded that money was more important (M = 4.2, SD =.9) than experience (M = 3.5, SD =.76) in selecting a summer job. In a survey of DU students, participants (N = 100) responded that money was more important (M = 4.2, SD =.9) than experience (M = 3.5, SD =.76) in selecting a summer job. In a survey of computer game addicts, females (n = 15) were more likely to be depressed during withdrawal (M = 5.2, SD =.45) than males were (n = 78, M = 3.2, SD =.98) In a survey of computer game addicts, females (n = 15) were more likely to be depressed during withdrawal (M = 5.2, SD =.45) than males were (n = 78, M = 3.2, SD =.98) If unsure about how to write a statistic in your SGR, you can consult the APA Manual (in the library), ask me, or visit If unsure about how to write a statistic in your SGR, you can consult the APA Manual (in the library), ask me, or visit

Charts and Graphs Pie graphs – good for showing distributions of a total population (you will have to compute aggregates first) Pie graphs – good for showing distributions of a total population (you will have to compute aggregates first) Line graphs – good for showing time-based, linear progression Line graphs – good for showing time-based, linear progression Column/Bar graphs – good for showing distribution of individual responses (you will have to create aggregates first) Column/Bar graphs – good for showing distribution of individual responses (you will have to create aggregates first) Y-Axis (vertical) for variables, X-Axis (horizontal) for participants. Y-Axis (vertical) for variables, X-Axis (horizontal) for participants.

Exercise Perform countif function on gender and major (you will have to create an area for your results that lists the gender/major options). This is just practice doing these two functions and you don’t have to relate them to the next steps. Perform countif function on gender and major (you will have to create an area for your results that lists the gender/major options). This is just practice doing these two functions and you don’t have to relate them to the next steps. Pick two or more variables to compare and write a paragraph in APA style using appropriate symbols (M, SD, N, n ) about the data. Pick two or more variables to compare and write a paragraph in APA style using appropriate symbols (M, SD, N, n ) about the data. Create a graph of some variable or detail of the data, labeling the legend and series items. Create a graph of some variable or detail of the data, labeling the legend and series items.