Understanding and Using Statistics in Psychology takes the fear out of psychological statistics to help students understand why statistics are carried out, how to choose the best test, how to carry out the tests, and then perform the analysis in SPSS. Emphasizing the place of statistical analysis in the process of conducting research, from design to report writing, this accessible and straightforward guide takes a non-technical approach, encouraging the reader to understand why a particular test is being used and what the results mean in the context of a psychological study. The focus is on meaning and understanding rather than numerical calculation.

### Making Inferences: Confidence Limits and Statistical Significance

Making inferences: Confidence limits and statistical significance

### What's in This Chapter?

• Calculating the standard error
• Probability
• Hypotheses
• t distribution
• Degrees of freedom
• Confidence intervals
• Using SPSS

### Key Terms

alpha

alternative hypothesis

confidence interval

confidence limits

degrees of freedom

descriptive statistics

hypotheses

inference

normal distribution

null hypothesis

one-tailed (or directional) hypothesis

population

probability

standard error

statistically significant

t distribution

two-tailed (or non-directional) hypothesis

type I error

type II error

z-score

### Introduction

This chapter is about the way we make inferences and statements of significance. It is also about how much tolerance there is in our results. By ‘tolerance’ we mean the how certain we are about our results. For example, when students take A levels they are given a grade from A to U, but there is bound to be some variation in the way the examinations are marked. It is generally agreed, though rarely reported, that the tolerance ...

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