1 / 12

CHAPTER 10

MANAGEMENT RESEARCH Third Edition, 2008 Prof. M. Easterby-Smith, Prof. R. Thorpe, Prof. Paul R. Jackson. CHAPTER 10 . Summarizing and Making Inferences from Quantitative Data. Learning Objectives. To be able to choose effective ways of summarizing key features of data.

sonora
Download Presentation

CHAPTER 10

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MANAGEMENT RESEARCH Third Edition, 2008 Prof. M. Easterby-Smith, Prof. R. Thorpe, Prof. Paul R. Jackson CHAPTER 10 Summarizing and Making Inferences from Quantitative Data

  2. Learning Objectives • To be able to choose effective ways of summarizing key features of data. • To know which summary measures to use for location and spread of data. • To understand which statistical tests to use when comparing groups and testing association between variables.

  3. Summarizing and making inferences • Summarizing Data: The Researcher identifies what features tell the best story about the data • Going beyond a sample: Making inferences about populations from samples The Researcher looks for patterns in the data that can be used to draw conclusions about the study’s research questions

  4. Summarizing and describing data • Showing the Shape of Data: • A Bar Chart shows the frequency distribution visually • A Histogram is a Bar Chart with scores grouped together to show features of data very easily

  5. Key features of data: Location • Mode - the commonest value among a set of scores • Median - the value that divides a set of data in half • Mean - the average value: add all the scores and divide by the sample size: M = ΣX / n • Mid-Mean – themean of the middle half of the data

  6. Key features of data: Spread • Range - the distance between the largest and the smallest scores • Mid-Range - the range of the middle half of the data; also known as interquartile range • Standard Deviation - measures the average spread around the mean: SD = √ (Σ(X-M)2 / n-1)

  7. Key features of data: Symmetry • Positively Skewed Data – the tail of extreme scores is to the right • Negatively Skewed Data – the tail of extreme scores is to the left

  8. Assessing summary measures: Robustness and efficiency • Robustness: The extent to which a summary measure is sensitive to disturbances in data quality • Efficiency: The extent to which a summary measure captures all the information within the data which is relevant to what is summarized

  9. Going beyond a sample • Hypothesis testing: Making inferences about populations based on data from samples • Five steps • Step 1 – define a research hypothesis to be tested • Step 2 – define a null hypothesis • Step 3 - derive a summary measure of the characteristic of interest • Step 4 – choosing a reference distribution and calculating a test statistic • Step 5 – drawing a conclusion

  10. Selecting statistical tests • Testing group differences • Comparing two groups – t test, Mann-Whitney U test • Comparing three or more groups – analysis of variance, Kruskal-Wallace test • Testing association • For category variables – chi square tests, phi coefficient • For continuous variables – correlation coefficient

  11. Association between two variables • A Positive Association - high scores on variables go together, and low scores go together • A Negative Association - high scores on one variable go with low scores on the other • Zero Association - knowing about one variable does not help in telling us anything about the other

  12. Further Reading • Howell, D. (2001). Statistical Methods for Psychology, 5th edition. Wadsworth. • Howell, D. (2007). Fundamental Statistics for the Behavioral Sciences, 6th edition. Wadsworth.

More Related