What are the measures of central tendency and dispersion

Mean, median, mode, range and standard deviation

Discuss and evaluate mean

Add up all numbers and divide by N ratio and interval data only

Most sensitive because uses exact distance, distorted by extreme values, but not appropriate for ordinal data or discrete values

Discuss and evaluate the median

Are you unselect midpoint the ratio, interval and ordinal data

Useful for extreme values, but not as sensitive as mean

Discuss and evaluate the mode

Most common value or group. Maybe bimodal. Can be used with all levels of measurement

Useful for nominal data, but not good when there are many modal groups

Discuss and evaluate the range

Subtract lowest from highest and add the correction of one

Easy to calculate, but affected by extreme numbers and doesn’t reflect the data distribution

Discuss and evaluate standard deviation

Average distance between each number and the main

Takes exact values into account may be affected by extreme values

How do you display quantitive data

Tables and graphs must have a title and clear labels

Tables may contain measures of central tendency and dispersion

Bar chart, histogram, line graph, scattergram

Explain a bar chart

Height of bar represents frequency, date on X axis may not be continuous

Explain the histogram

Represents frequency of continuous data, true zero and bobs next to each other

Explain a line graph

Frequency represented by a line rather than bars

Explain a scattergram

Shows correlation between covariables

What are the types of data distributions

Normal distribution, positive skew, negative skew

Discuss a normal distribution

Symmetrical bell shaped curve; mean, median and mode at midpoint; about 68% of people are one standard deviation above and below the midpoint, 95% within two standard deviation from midpoint

Discuss a positive skew

Tail to right, occurs eg: test too hard

Discuss a negative skew

Tail to left, because e.g. when test to easy

What are the types of data

Quantitive

Qualitative

Primary

Secondary

Discuss and evaluate quantitive data

Numerical, easy to analyse but may not represent reality

Discuss and evaluate quantitative data

Can’t be directly counted, detailed and possibly unexpected information, but more difficult to draw conclusions

Discuss and evaluate primary data

Collected by the researcher for current study, involves design a study to collect data. Suits the needs of the study, but time-consuming and expensive

Discuss and evaluate secondary data

Using data collected for previous study. Saves time and money but may not fit exact needs of study

When do you use the sign test

With paired or related data

How do you do the sign test

Represent each pair of data with plus or minus, calculated value of S= less frequent sign

Look up critical value of S, need to know N and whether one-tailed or two-tailed test

Conclusion is if the calculation value is less than or equal to critical value the difference is significant

Probability level of 5% is commonly used