how to interpret descriptive statistics results in spss example

Minitab does not include missing values in this count. Contact us for help with your data analysis and interpretation. The a. The variables in this example are: Entrepreneurial Interest (Y):: I am interested in starting a business or investing in a business in the next six months. the sum of the squared distances of data value from the mean divided by the m.  Interquartile Range – The interquartile range is the value in the last column. State of Residence(X): Florida, Nevada, Texas Descriptive Statistics Dependent Variable: Consider starting your own business In SPSS, the statistical program often used to calculate statistics, output is not provided in APA format. If we repeatedly drew samples First, we introduce the example that is used in this guide. 10s place, so it is the stem. Descriptive Statistics . If you have a Group variable, you can use it to analyze your data by group or by group level. For example, Machine 1 has a lower mean torque and less variation than Machine 2. If you have additional information that allows you to classify the observations into groups, you can create a group variable with this information. Once a student obtains output from SPSS, he or she needs to take the output and format it in APA style when writing a statistical results section. Example 1.A large international air carrier has collected data on employees in three different jobclassifications: 1) customer service personnel, 2) mechanics and 3) dispatchers. Outliers, which are data values that are far away from other data values, can strongly affect the results of your analysis. Step 4: Assess the shape and spread of your data distribution, Step 5. This individual plot shows that the data on the right has more variation than the data on the left. The mean for the no caffeine condition (NOCAFDTA) is 9.40. It is commonly called the Specify one or more variables whose descriptive statistics are to be calculated. ... Descriptive Statistics - … understandable as possible. Example taken from Field A (2009) Discovering statistics using SPSS 2nd ed. For comparing two metric variables measured on one group of cases, our first choice is the paired-samples t-test. There are three common forms of descriptive statistics: 1. don’t generally use variance as an index of spread because it is in squared The variance-covariance matrix is als… We show you how to understand these tables of output, what part of this output you need to look at, and how to write up the results in a number of different formats. d.  This is the first quartile (Q1), also known as the 25th percentile. For example, in the first line, the stem is 3 The next output from the analysis is the correlation coefficient. We have included row percentages, column percentages and cell percentages.. We have reproduced this table below, with footnotes explaining the percentages. value of the 5% trimmed mean is very different from the mean, this indicates In this example, I will get summary statistics on the height broken down by gender and favorite grocery store. Standard deviation can be difficult to interpret as a single number on its own. Continuous variables in SPSS • Analyse > Descriptive Statistics – Descriptives – Explore • … It is variability possible in the statistic. It is the variable. The number of participants in each condition (N) is 5. Check out the Udemy course Descriptive Statistics in SPSS, which teaches you how to do this form of analysis with computer software. SPSS is commonly used in healthcare, marketing, and education research. are several commands that you can use to get descriptive statistics for a The following are some key points for writing descriptive results: Add a table of the raw data in the appendix; Include a table with the appropriate descriptive statistics e.g. Case analysis was demonstrated, which included a dependent variable (crime rate) and independent variables (education, implementation of penalties, confidence in the police, and the promotion of illegal activities). Larger samples also provide more precise estimates of the process parameters, such as the mean and standard deviation. For example, in the column labeled 5, the value of the variable write is 35. skewness of 0, and a distribution that is skewed to the left, e.g. The descriptive table provides anova results spss through the standard deviation, mean, and 95% confidence intervals for each group in a dependent time. b. interquartile range. Case analysis was demonstrated, which included a dependent variable (crime rate) and independent variables (education, implementation of penalties, confidence in the police, and the promotion of illegal activities). However, to better represent the distribution with a histogram, some practitioners recommend that you have at least 50 observations. After further investigation, the manager determines that the wait times for customers who are cashing checks is shorter than the wait time for customers who are applying for home equity loans. In these results, the standard deviation is 6.422. It’s to help you get a feel for the data, to tell us what happened in the past and to highlight potential relationships between variables. The 3 is in the The ANOVA Table. With normal data, most of the observations are spread within 3 standard deviations on each side of the mean. b.  Tukey’s Hinges – These are the first, second and third g.  Median – This is the median. 35, which is why the weighted average is 35.05. d.  25 – This is the 25% percentile, also known as the first d.  Maximum – This is the maximum, or largest, value of the variable. into SPSS. is positive if the tails are “heavier” than for a normal distribution and To determine whether the difference in means is significant, you can perform a 2-sample t-test. For example, you may be interested to get descriptive or inferential statistics for males and females separately. If the SPSS: Descriptive and Inferential Statistics 4 The Department of Statistics and Data Sciences, The University of Texas at Austin click on the arrow button that will move those variables to the Variable(s) box.For example, the h.  Skewness – Skewness measures the degree and direction of Example 2. Use the standard deviation to determine how spread out the data are from the mean. deviation is, the more spread out the observations are. We have added some options to each of these commands, and we Perhaps include sample sizes as well: for multiple tests, these may vary due to missing values. The first part of this SAS output, (download below), is the results of the Means Procedure - proc means. Make sure to include the SPSS output in the word document. This gives you some idea about the variability of the variable at various percentiles. The next output from the analysis is the correlation coefficient. c.  Mean – This is the arithmetic mean across the observations. You will find that the examine command and leaves are 1. output. A sample of N = 236 people completed a number of speedtasks. The ANOVA table shows the ANOVA analysis output. Sometimes, the median is Basically, a small standard deviation means that the values in a statistical data set are close to the mean of the data set, on average, and a large standard deviation means that the values in the data set are farther away from the mean, on average. Valid N (listwise) – This is the number of non-missing values. the mean, mode, median, and standard deviation. b.  Std. Kurtosis Here we can see how to perform a One way ANOVA using SPSS. Remember that you need to use the .sav extension and f.  Std. units. It measures the spread of the sum of the squared distances of data value from the mean divided by the For example, you are the quality control inspector at a milk bottling plant that bottles small and large containers of milk. If there is not a value at exactly the 5th Multi-modal data often indicate that important variables are not yet accounted for. A health researcher wants to be able to predict "VO 2 max", an indicator of fitness and health. The larger the standard For example, in this spreadsheet, "1" is … From this window, select the variable for which we want to calculate the descriptive statistics and drag them into the variable window. After clicking the descriptive statistics menu, another menu will appear. The purpose of this document is to demonstrate and provide examples of how to format statistical results in accordance with the guidelines set forth by the American Psychological Association’s (APA) publication manual. In this How to Interpret SPSS Output Overview of SPSS Output. b. 1.4 - Example: Descriptive Statistics . variable. Principal Component Analysis Example – Write Up Page 6 of 10 5 Interpreting the output 5.1 Descriptive Statistics The table opposite simply shows the means, standard deviations and sample size for each variable. column, the N is given, which is the number of non-missing cases; and the On a boxplot, asterisks (*) denote outliers. You could add some columns to this table holding df, t and p for each test (p is denoted as “Sig. the average. This is a bad thing, but SPSS takes this into account by giving you slightly different results in the second row. A symmetric distribution such as a normal distribution has a c.  Total – This refers to the total number cases, both Text values will be skipped in the calculations. Click here to report an error on this page or leave a comment, Your Email (must be a valid email for us to receive the report! These tell you about the distribution of The independent variable – or, to adopt the terminology of ANOVA, the within-subjects factor – is time, and it has three levels: SPQ_Time1 is the time of the first SPQ assessment; SP… As with percentiles, the purpose of the histogram is the For example, Machine 1 has a lower mean torque and less variation than Machine 2. The mean is sensitive to extremely large or small values. It is certainly legitimate to do an ANOVA with this size It is easy to compute and easy to understand. It is a measure of central tendency. a.  Statistic – These are the descriptive statistics. In these results, the summary statistics are calculated separately by machine. Jesus Salcedo is an independent statistical and data-mining consultant who has been using SPSS products for more than 25 years. We will use the hsb2.sav data file for our When you have unusual values, you can compare the mean and the median to decide which is the better measure to use. Contact us for help with your data analysis and interpretation. This page shows examples of  how to obtain descriptive statistics, with footnotes explaining the By Deborah J. Rumsey . Notice that the standard deviations are large relative to their respective means, especially for Vitamin A & C. This would indicate a high variability among women in nutrient intake. In SPSS, the first few rows of data look like this: Before the Test. female and 0 if male. asymmetry. If the Sig. In these results, you have 68 observations. The manager adds a group variable for customer task, and then creates a histogram with groups. While SPSS Statistics produces many tables of output, you often only need to interpret and report a small proportion of the figures/numbers within these tables. descriptive statistics. • Altman, D. G. (1980). the value of the variable. that there are some outliers. Starting SPSS Statistics. Use this data file (Muijs, 2011) to complete the following items/questions. e.  95% Confidence Interval for Mean Upper Bound – This is the variable from lowest to highest, and then looking at whatever percent to see the The Corrected SS is the sum of squared distances of data value You can easily see the differences in the center and spread of the data for each machine. Extremely nonnormal distributions may have high positive or negative kurtosis values, This is the maximmum score unless there are values more than 1.5 times the interquartile from the mean. a. We will show two:  descriptives and Because this is a weighted SPSS provides data analysis for descriptive and bivariate statistics, numeral outcome predictions and predictions for identifying groups. Conduct your regression procedure in SPSS and open the output file to review the results. There is no reason to expect the means and standard … A symmetric distribution such as a normal distribution has a Our independent variable, therefore, is Education, which has three levels – High School, Grad… The histogram with left-skewed data shows failure time data. The SPSS Output Viewer will appear with your results in it. negative if the tails are “lighter” than for a normal distribution. measures the spread of a set of observations. Complete the following steps to interpret descriptive statistics. The following is an example of the output: The output gives the values of the requested statistics. ANOVA using SPSS. range above Q3, in which, it is the third quartile plus 1.5 times the interquartile range The Statistical Package of Social Sciences (SPSS), allows the user to perform both descriptive and inferential statistics.The SPSS mainly produces its output in … Instead, we use standard deviation. The Statistical Package of Social Sciences (SPSS), allows the user to perform both descriptive and inferential statistics.The SPSS mainly produces its output in … is less than the median, has a negative skewness. However, whether the standard deviations are relatively large or not, will depend on the context of the application. example. the value of the variable write is 35. Descriptive statistics has a lot more depth to it than you may think, and there’re a lot of great resources for you to use to learn about it. Therefore, the variance is the corrected SS divided by N-1. i.  St. Deviation – Standard deviation is the square root of the units. h.  Variance – The variance is a measure of variability. Example . How do I interpret data in SPSS for a 1-way between subjects ANOVA? e.  Mean – This is the arithmetic mean across the observations. The mean is sensitive to extremely large or small values. Many statistical analyses use the mean as a standard measure of the center of the distribution of the data. To run the Descriptives procedure, select Analyze > Descriptive Statistics > Descriptives. Interpreting results, descriptive statistics descriptive statistics [Lar82], sample mean and sample variance After collecting data in a simulation experiment, we often want to calculate some statistics to characterize the results, typically estimates of the mean and variance of certain observed quantities. Association’s (APA) publication manual. There Valid – This refers to the non-missing cases. The Corrected SS is the sum of squared distances of data value The data in this example is loosely based on the evaluation of the Schools Linking Network. he came up with the idea of a boxplot. First download the SPSS software to perform the ANOVA. one value of 38 and five values of 39 in the variable write. Some of the values are fractional, which is a result of how Skill in interpreting the statistical analysis depends very much on the researcher's subject matter knowledge. SPSS is easy to learn and enables teachers as well as students to easily derive results with the help of a … When it comes to descriptive statistics examples, problems and solutions, we can give numerous of them to explain and support the general definition and types. It is the most widely used measure of central tendency. average. Key output includes N, the mean, the median, the standard deviation, and several graphs. A correlation matrix is simple a rectangular array of numbers which gives the correlation coefficients between a single variable and every other variables in the investigation. Print this file and highlight important sections and make handwritten notes as you review the results. The average score for a person with a spider phobia is 23, which compares to a score of slightly under 3 for a non-phobic. give you an idea about the distribution of the variable. SPSS Wilcoxon Signed-Ranks Test – Simple Example By Ruben Geert van den Berg under Statistics A-Z & Nonparametric Tests. They are calculated the way that Tukey originally proposed when ANOVA Example . Below is the output for the SPSS ONEWAY procedure to compare the means of three school types in the hypothetical teacher satisfaction example. In such cases, one may use a select case option in SPSS. A previous article explained how to interpret the results obtained in the correlation test. Out of 60 respondents, 31.7% were less than 19 years of age, 28.3% of them were between 19 and 27 years of age and 40% of them are above 27 years of age. There are several different Reporting Results of Descriptive and Inferential Statistics in APA Format The Results section of an empirical manuscript (APA or non-APA format) are used to report the quantitative results of descriptive statistics and inferential statistics that were applied to a set of data. o.  Kurtosis – Kurtosis is a measure of the heaviness of the We For example, Machine 1 has a lower mean torque and less variation than Machine 2. Then click OK. Once you click OK, a table will appear that displays the following descriptive statistics for each variable: Here is how to interpret the numbers in this table for the variable score: N: The total number of observations. c.  Leaf – This is the leaf. A correlation matrix is simple a rectangular array of numbers which gives the correlation coefficients between a single variable and every other variables in the investigation. Most of the wait times are relatively short, and only a few wait times are long. The Descriptive Table. In this case there are 20. Check out the Udemy course Descriptive Statistics in SPSS, which teaches you how to do this form of analysis with computer software. In the section, Procedure, we illustrate the SPSS Statistics procedure to perform a multiple regression assuming that no assumptions have been violated. These tables share important descriptive statistics and figures to come up with ANOVA output. Descriptive statistics are important for establishing the validity of your sample as a representation of the sampled population. The total number of observations is the sum of N and the number of missing Before running the Independent Samples t Test, it is a good idea to look at descriptive statistics … In parametric statistical analysis the requirements that must be met are data that are normally distributed. In this column, the N is given, which is Following outputs from SPSS windows represent how the results for Descriptive Statistics are presented: Descriptive Statistics: A sample of 60 respondents was taken for the survey. indicating that it is using “Definition 1”. SPSS Statistics generates quite a few tables in its one-way ANOVA analysis. Percentiles are determined by ordering the values of the A histogram shows the frequency of values of a variable. It is the middle number when the For the purposes of this tutorial, we’re interested in whether level of education has an effect on the ability of a person to throw a frisbee. j. For example, in the column labeled 5, SPSS Statistics Example. The descriptive statistic should be relevant to the aim of study; it should not be included for the sake of it. Then, you can create the graph with groups to determine whether the group variable accounts for the peaks in the data. these numbers is in the variable. lower (95%) confidence limit for the mean. Instead, we use standard deviation. Multiple regression is an extension of simple linear regression. Conduct your regression procedure in SPSS and open the output file to review the results. Westfall, P. Kurtosis as Peakedness, 1905 – 2014. l.  Range – The range is a measure of the spread of a variable. A previous article explained how to interpret the results obtained in the correlation test. estimate of the true population mean. It is The SSCC has SPSS installed in our computer labs (4218 and 3218 Sewell Social Sciences Building) and on some of the Winstats.If you work on a University-owned computer you can also go to DoIT's Campus Software Library, and download and install SPSS on that computer (this requires a NetID, and administrator priviledges). Mahwah, NJ: Lawrence Erlbaum. Select RankUpperUnder as the row variable, and LiveOnCampus as the column variable. command. It is the number in the 1s place of In SAS, a normal distribution has kurtosis 0. The output file will appear on your screen, usually with the file name "Output 1." The variable we’re interested in here is SPQ which is a measure of the fear of spiders that runs from 0 to 31. All rights Reserved. The number of leaves tells you how many of He has written numerous SPSS courses and trained thousands of users. f.  5% Trimmed Mean – This is the mean that would be obtained if It is the number in the 10s place of g.  Variance – The variance is a measure of variability. Pawel Skuza 2013 Summary Statistics Categorical variables in SPSS • Analyse > Descriptive Statistics – Frequencies (Statistics: quartiles, percentiles) – Explore (median, percentiles) • Graphs – Bar chart Begin your interpretation by examining the "Descriptive Statistics" table. a. command Using SPSS for Descriptive Statistics. There is Fisher’s (1936) classic example o… interquartile range below Q1, in which case, it is the first quartile minus 1.5 times the Descriptive Statistics and Interpreting Statistics Resources. confidence limits. However, it is very After selecting all the things, click on continue to return to the “Descriptives” dialog box and click Ok. you need just a few numbers, you may want to use the descriptives Begin your interpretation by examining the "Descriptive Statistics" table. A few items fail immediately, and many more items fail later. Elsewhere in this blog, I have written that a Likert scale might consist of several overlapping items. value in this example was greater less than .05, we would have read from the second row. However, you cannot assume that all outliers The standard deviation for the caffeine condition is 1.14 and for the no caffeine condition, also 1.14. With SPSS, you have to be very careful that you are aware of this distinction between continuous and categorical variables, because if you use numbers as labels, SPSS will often happily do statistics on them regardless. Example: My data_2008_08_19, My data_2008_08_20 • Keeping diary of undertaken analyses - Syntax ... – Incorrect analysis results Pawel Skuza 2013 How to report? a. SPSS: Analyze: Descriptive Statistics. These data contain the ratings of 3 car commercials by 18 respondents, balanced over gender and age category. n.  Skewness – Skewness measures the degree and direction of The histogram appears to have two peaks. Example … (We also use stat-transfer if the data is in another form). Use the mean to describe the sample with a single value that represents the center of the data. It’s to help you get a feel for the data, to tell us what happened in the past and to highlight potential relationships between variables. The software also provides data transformation, graphing and direct marketing features. size of the bins is determined by default when you use the examine Let’s first clarify the main purpose of descriptive data analysis. c.  Percentiles – These columns given you the values of the To determine whether the difference in means is significant, you can perform a 2-sample t-test. In this section, we show you only the main tables required to understand your results from the one-way ANOVA and Tukey post hoc test. Stem – This is the stem. If your data is scale level, try summaries or descriptives. average, SPSS is taking into account the fact that there are several values of It is equal to the difference between the largest and the smallest observations. e. Error – These are the standard errors for the The variable female is a dichotomous variable coded 1 if the student was from the mean. than the mean to extreme observations. A sample of SPSS ANOVA output is below and on the following page. We the value of the variable. The Two Types of Descriptive Statistics you are looking for, but can be overwhelming if you are not used to it. Print this file and highlight important sections and make handwritten notes as you review the results. f.  75 – This is the 75% percentile, also know as the third Example: Summarizing Correlation and Regression Analyses For relationship data (X,Y plots) on which a correlation or regression analysis has been performed, it is customary to report the salient test statistics (e.g., r, r-square) and a p-value in the body … For example, the "I'd rather stay at home than go out with my friends" variable has a … For each commercial separately, our null hypothesis is:“the mean ratings of men and women are equal.” Consider the example below. that you need to end the command (and all commands) with a period. Bartz, A. E. (1971). The data used in these examples were collected on 200 high schools students and are 3. e.  50 – This is the 50% percentile, also know as the median. Samples that have at least 20 observations are often adequate to represent the distribution of your data. This is the third quartile (Q3), also known as the 75th percentile.